Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Chen, Zhe

2017-01-01

This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies...

La inflación de los adultos mayores en Colombia

Directory of Open Access Journals (Sweden)

Álvaro Montenegro

2016-12-01

Full Text Available Este artículo compara el comportamiento de la inflación para el hogar promedio y diversos tipos de hogares de adultos mayores en Colombia. Los resultados indican que, en promedio, los adultos mayores gastan una mayor proporción de su ingreso en vivienda y salud y una menor proporción en educación, y que experimentaron una mayor inflación que la población en general entre diciembre de 2008 y mayo de 2015. Los hogares de adultos mayores más pobres gastan una mayor proporción en vivienda y alimentación, y para estos la inflación fue mayor que para los de adultos mayores de altos ingresos.

Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid

DEFF Research Database (Denmark)

Deng, Fujin; Chen, Zhe

2013-01-01

transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...

IGBT Based DC/DC Converter

Directory of Open Access Journals (Sweden)

M. Akherraz

1997-12-01

Full Text Available This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high  frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.

Three-port DC-DC converter with new integrated transformer for DC Distribution Systems

DEFF Research Database (Denmark)

Ouyang, Ziwei; Andersen, Michael A. E.

2014-01-01

A new integrated transformer for three-port dc-dc converter is proposed to overcome the power coupling effect existed in some known multiple inputs dc-dc converters. Orthogonal primary windings arrangement and in series connection of diagonal secondary Windings enables a fully power decoupling...

Three new DC-to-DC Single-Switch Converters

Directory of Open Access Journals (Sweden)

Barry W. Williams

2017-06-01

Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.

Abuso y Maltrato en el Adulto Mayor

OpenAIRE

Montero Solano, Gustavo; Vega Chaves, Juan Carlos; Hernández, Gabriel

2017-01-01

ResumenExiste incongruencia en las definiciones e interpretación del abuso en adultos mayores. Una definición apropiada y unificada es la dada por la Organización Mundial de la Salud, que indica que el abuso en adulto mayor es cualquier acto aislado o repetitivo o la falta de acción apropiada, ocurrida en cualquier relación de la que se espera confianza, que causa daño o malestar a la persona mayor.Este grupo poblacional es particularmente vulnerable, pues es muy probable que, en algún moment...

Percepción del estudiante de medicina de una universidad pública acerca del docente adulto mayor y del adulto mayor en general

Directory of Open Access Journals (Sweden)

Martha Martina

2014-07-01

Full Text Available Introducción: La mayoría de los estudios disponibles muestran que las imágenes que construyen los jóvenes sobre la vejez, en general, se asocian a una valoración negativa de esta etapa de la vida. Objetivos: Analizar la percepción de los estudiantes de Medicina Humana de la UNMSM acerca de la vejez, así como la existencia o no de estereotipos negativos acerca de la vejez y del docente adulto mayor. Diseño: Estudio transversal. Institución: Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú. Participantes: Estudiantes del primero, tercero y quinto año de la Escuela Académico Profesional de Medicina Humana. Intervenciones: Aplicación de una escala de diferencial semántico para medir la percepción de los estudiantes mediante un cuestionario autoadministrado. Principales medidas de resultados: De una muestra de 319 estudiantes, 54,2% fue del sexo masculino y el promedio de edad 21,7±2,6 años; 90,3% tuvo cercanía con profesores mayores de 70 años. Los alumnos del quinto año otorgaron menores puntuaciones a los docentes adultos mayores (p=0,003 y a los adultos mayores en general (p=0,045. Los estudiantes que en su familia convivían con personas mayores de 70 años tuvieron una percepción más positiva sobre los adultos mayores en general (p=0,037. Respecto a la percepción de los estudiantes acerca del docente adulto mayor destacaron cinco características que superaron el 70% del puntaje, tipificándolo como seguro de sí mismo (78%, organizado (73,9%, interesado en el aprendizaje del estudiante (72,8%, planificador (72,6% y emocionalmente estable (71,8%. Respecto al adulto mayor, los puntajes no superaron el 70%, y en general lo tipificaron como tratable, sociable y hábil. Conclusiones: Los estudiantes de medicina mostraron una percepción positiva hacia el docente adulto mayor y sobre el adulto mayor en general. Existieron diferencias estadísticamente significativas según el año de estudios. Los

75 FR 60602 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

2010-10-01

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... adding the following new AD: 2010-20-14 McDonnell Douglas Corporation: Amendment 39-16449. Docket No. FAA... the airplanes identified in paragraphs (c)(1) and (c)(2) of this AD. (1) McDonnell Douglas Corporation...

75 FR 38943 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

Science.gov (United States)

2010-07-07

...-0672; Directorate Identifier 2010-NM-047-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0672; Directorate Identifier 2010-NM-047-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10...

75 FR 6160 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

2010-02-08

...-0032; Directorate Identifier 2009-NM-213-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0032; Directorate Identifier 2009-NM-213-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...

75 FR 61989 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-8-31, DC-8-32, DC-8-33, DC-8-41...

Science.gov (United States)

2010-10-07

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, and... to all of the McDonnell Douglas Corporation airplanes identified above. The existing AD currently... the following new airworthiness directive (AD): 2010-21-03 McDonnell Douglas Corporation: Amendment 39...

Multi Bus DC-DC Converter in Electric Hybrid Vehicles

Science.gov (United States)

Krithika, V.; Subramaniam, C.; Sridharan, R.; Geetha, A.

2018-04-01

This paper is cotncerned with the design, simulation and fabrication of the prototype of a Multi bus DC- DC converter operating from 42V DC and delivering 14V DC and 260V DC. As a result, three DC buses are interconnected through a single power electronic circuitry. Such a requirement is energized in the development of a hybrid electric automobile which uses the technology of fuel cell. This is implemented by using a Bidirectional DC-DC converter configuration which is ideally suitable for multiple outputs with mutual electrical isolation. For the sake of reduced size and cost of step-up transformer, selection of a high frequency switching cycle at 10 KHz was done.

Step-Up DC-DC Power Converter

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic...

AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

Directory of Open Access Journals (Sweden)

Moh. Zaenal Efendi

2014-06-01

Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

Salud mental en el adulto mayor: trastornos neurocognitivos mayores, afectivos y del sueño

Directory of Open Access Journals (Sweden)

Tania Tello-Rodríguez

Full Text Available RESUMEN Existen numerosos factores biológicos, psicológicos y sociales con impacto más o menos prominente en la salud mental de las personas adultas mayores. Aparte de componentes derivados de los procesos normales de envejecimiento o de la coocurrencia de enfermedades médicas diversas, eventos como la muerte de un ser querido, la jubilación o la discapacidad, contribuyen significativamente a una variedad de problemas mentales o emocionales en esta fase del ciclo vital. Los problemas más frecuentes afectan las esferas neurocognitiva, afectiva y onírica. Los trastornos neurocognitivos mayores reducen el rendimiento general del paciente y generan con ello exigentes necesidades de dependencia y cuidado cercano. Los trastornos afectivos pueden acentuarse por falta de apoyo familiar y disminución marcada de interacciones sociales que pueden dar lugar a un significativo aislamiento con conducta suicida resultante. La mayor frecuencia de trastornos del sueño como insomnio, somnolencia diurna y trastornos específicos como apnea obstructiva alteran significativamente la calidad de vida de esta población.

Early Oscillation Detection for DC/DC Converter Fault Diagnosis

Science.gov (United States)

Wang, Bright L.

2011-01-01

The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

A Study of Two Multi-Element Resonant DC-DC Topologies with Loss Distribution Analyses

Directory of Open Access Journals (Sweden)

Yifeng Wang

2017-09-01

Full Text Available In this paper, two multi-element resonant DC-DC converters are analyzed in detail. Since their resonant tanks have multiple resonant components, the converters display different resonant characteristics within different operating frequency ranges. Through appropriate design, both of the two proposed converters successfully lower the conversion losses and, meanwhile, broaden the voltage gain ranges as well: one converter is able to take full usage of the third order harmonic to deliver the active power, and thus the effective utilization rate of the resonant current is elevated; while the another minimizes the entire switching losses for power switching devices by restricting the input impedance angle of the resonant tank. Besides, the loss distribution is analyzed for the purpose of guiding the component design. In the end, two 500 W prototypes are fabricated to test the theoretical analyses. The results demonstrate that the two proposed converters can achieve wide voltage gain with the small frequency deviation, which noticeably contributes to highly efficient conversion. Their peak efficiencies are measured as 95.4% and 95.3%, respectively.

Superconducting energy stabilizer with charging and discharging DC-DC converters

International Nuclear Information System (INIS)

Kim, S.H.; Kostecki, E.L.; DeWinkel, C.C.

1992-01-01

This patent describes a superconducting energy stabilizer having multiple load connections and employing DC-DC conversion for storing energy in a superconducting inductive energy storage device having a first end and a second end, and for releasing the stored energy from the superconducting inductive energy storage device to a load or loads or to a utility or an industrial electrical distribution system, the superconducting energy stabilizer having multiple load connections and employing DC-DC conversion. It comprises: energy storage cell means for supplying energy to the load, discharging DC-DC converter means for releasing energy from the superconducting inductive energy storage device to the energy storage cell means, the discharging DC-DC converter means having input terminals, output terminals, and a discharging control line means for carrying signals controlling the operation of the discharging DC-DC converter means, one of the input terminals of the discharging DC-DC converter means coupled to the first end of the superconducting energy storage device

dc Arc Fault Effect on Hybrid ac/dc Microgrid

Science.gov (United States)

Fatima, Zahra

The advent of distributed energy resources (DER) and reliability and stability problems of the conventional grid system has given rise to the wide spread deployment of microgrids. Microgrids provide many advantages by incorporating renewable energy sources and increasing the reliability of the grid by isolating from the main grid in case of an outage. AC microgrids have been installed all over the world, but dc microgrids have been gaining interest due to the advantages they provide over ac microgrids. However the entire power network backbone is still ac and dc microgrids require expensive converters to connect to the ac power network. As a result hybrid ac/dc microgrids are gaining more attention as it combines the advantages of both ac and dc microgrids such as direct integration of ac and dc systems with minimum number of conversions which increases the efficiency by reducing energy losses. Although dc electric systems offer many advantages such as no synchronization and no reactive power, successful implementation of dc systems requires appropriate protection strategies. One unique protection challenge brought by the dc systems is dc arc faults. A dc arc fault is generated when there is a gap in the conductor due to insulation degradation and current is used to bridge the gap, resulting in an arc with very high temperature. Such a fault if it goes undetected and is not extinguished can cause damage to the entire system and cause fires. The purpose of the research is to study the effect of the dc arc fault at different locations in the hybrid ac/dc microgrid and provide insight on the reliability of the grid components when it is impacted by arc faults at various locations in the grid. The impact of dc arc fault at different locations on the performance of the PV array, wind generation, and constant power loads (CPL) interfaced with dc/dc converters is studied. MATLAB/Simulink is used to model the hybrid ac/dc microgrid and arc fault.

Milliwatt dc/dc Inverter

Science.gov (United States)

Mclyman, C. W.

1983-01-01

Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.

75 FR 63040 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

Science.gov (United States)

2010-10-14

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10... following new airworthiness directive (AD): 2010-21-13 McDonnell Douglas Corporation: Amendment 39-16473... November 18, 2010. Affected ADs (b) None. Applicability (c) This AD applies to McDonnell Douglas...

75 FR 68246 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

2010-11-05

...-1044; Directorate Identifier 2010-NM-033-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas..., 2007) and adding the following new AD: McDonnell Douglas Corporation: Docket No. FAA-2010-1044.... Applicability (c) This AD applies to all McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Overview of Multi-DC-Bus Solutions for DC Microgrids

DEFF Research Database (Denmark)

Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco

2013-01-01

DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....

DC to DC power converters and methods of controlling the same

Science.gov (United States)

Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

2012-12-11

A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

Hierarchical Velocity Control Based on Differential Flatness for a DC/DC Buck Converter-DC Motor System

Directory of Open Access Journals (Sweden)

R. Silva-Ortigoza

2014-01-01

Full Text Available This paper presents a hierarchical controller that carries out the angular velocity trajectory tracking task for a DC motor driven by a DC/DC Buck converter. The high level control is related to the DC motor and the low level control is dedicated to the DC/DC Buck converter; both controls are designed via differential flatness. The high level control provides a desired voltage profile for the DC motor to achieve the tracking of a desired angular velocity trajectory. Then, a low level control is designed to ensure that the output voltage of the DC/DC Buck converter tracks the voltage profile imposed by the high level control. In order to experimentally verify the hierarchical controller performance, a DS1104 electronic board from dSPACE and Matlab-Simulink are used. The switched implementation of the hierarchical average controller is accomplished by means of pulse width modulation. Experimental results of the hierarchical controller for the velocity trajectory tracking task show good performance and robustness against the uncertainties associated with different system parameters.

An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

OpenAIRE

Liwen Pan; Chengning Zhang

2016-01-01

This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs). The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for m...

PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC

Directory of Open Access Journals (Sweden)

Bambang Prio Hartono

2012-09-01

Full Text Available Abstract: Using system fuzzy logic as control  technology have been used on low load dc-dc converter with combined parallel compiled  dc-dc converter can  obtain big load.   With existence of differrence of component parameter and each parallel compiled converter can obtained different current  and voltage output.  Function of controller  for to do adjustment, so that current which is applied  to  load by each converter  can be obtained  difference error as small as possible or same. The object of research is developing design of large signal dc-dc converter which is  combined with using  FLC so that  obtain  better performance.  To get better performance have been made plant model and simulation with CDE method.  The more systematic  system and design is needed to overcome bigger load  on dc-dc converter, so that parallel  compiled current master slave control system on dc-dc converter with using fuzzy logic  controller is used. Result of  research showed that error or difference of  current  which is applied to load can handled by fuzzy logic  controller.  Technic of current and voltage controller co to do adjustment current and voltage distribution  equally to load.  Distribution of iL1,iL2 and  output voltage Vo on dc-dc  converter with load 2,25 until  7,875 and voltage  100  until 120 volt,  load current beetwen  12 until 48, % relatif  error  Vo  0,4% until  0,9%.

Full range ZVS DC-DC converter

International Nuclear Information System (INIS)

Upadhyay, Rinki; Badapanda, M.K.; Hannurkar, P.R.

2011-01-01

A 500 V, 24 Amp DC-DC converter with digital signal processor (DSP) based control and protection has been designed, fabricated and tested. Its power circuit consists of IGBT based single phase inverter bridge, ferrite transformer and diode rectifier. All IGBTs in the inverter bridge are operated in zero voltage switching (ZVS) mode to minimize switching losses thereby increasing the efficiency of the converter significantly. The efficiency of this converter is measured to be greater than 97% at full load. In a conventional full bridge inverter, typically ZVS is achieved under full load condition while at light load ZVS is lost. An auxiliary LC circuit has been intentionally incorporated in this converter to achieve ZVS even at light loaded conditions. Detailed simulation of the converter circuit is carried out and crucial waveforms have been presented in this paper. Microchip make dsPIC30F2020 DSP is employed to provide phase shifted PWMs to IGBTs in the inverter bridge. All the crucial parameters are also monitored by this DSP and in case of any unfavorable conditions, the converter is tripped off. Suitable experiments were carried out in this DC-DC converter under different loaded conditions and a close match between the simulated and experimental results were obtained. Such DC-DC converters can be connected in series or parallel for the development of solid state modular power supplies for various applications. (author)

TOPOLOGICAL REVIEW AND ANALYSIS OF DC-DC BOOST CONVERTERS

Directory of Open Access Journals (Sweden)

V. INDRA GANDHI

2017-06-01

Full Text Available DC voltage boost up is essential in numerous applications; especially considering Photovoltaic (PV based renewable power generation system. The conventional DC-DC boost converter is the most admired configuration for this scheme, even if the converter efficiency is restricted at duty cycle near to maximum value. In order to find solution to the problem and improve its conversion capability, many converter configurations have been implemented so far. With this circumstance, this research work proposes to give overview of a few most imperative research works related to DC-DC boost converters. Some configurations are covered and classified basically based on the application. The major benefits and disadvantages related to the available techniques are also briefly conveyed. At last, a proper evaluation is recognized among the important types of DC-DC boost converters in terms of efficiency, number of components, and stability.

Prevalencia de anemia y factores asociados en adultos mayores peruanos

Directory of Open Access Journals (Sweden)

Carolina Tarqui-Mamani

Full Text Available Objetivos. Determinar la prevalencia de anemia y factores asociados en los adultos mayores del Perú. Materiales y métodos. Se realizó un estudio transversal durante el año 2011. El muestreo fue probabilístico, estratificado y multietápico. La muestra de viviendas fue 5792 y se incluyó 2172 adultos mayores. Se definió anemia como hemoglobina 23 a 80 años (OR 2,1; IC 95%: 1,4-3,0 y la delgadez (OR 1,7; IC 95%:1,2-2,3 se asociaron con la anemia. Los departamentos con mayor prevalencia de anemia fueron Ayacucho (57,6%, Ancash (40,1%, Lambayeque (37,7% y Apurímac (36,9%. Conclusiones. Aproximadamente la cuarta parte de los adultos mayores tuvieron anemia, siendo más predominante en los analfabetos, procedentes de áreas rurales y pobres. La mayor edad y la delgadez se asocian con la presencia de anemia en los adultos mayores peruanos

Subjetividad urbana de los adultos mayores

OpenAIRE

Rinaldi, Nicolás Darío

2008-01-01

El objetivo general de la investigación consiste en vislumbrar características psicológicas de la subjetividad de los mayores, indagando sobre las modalidades de participación social e interacción subjetiva, con el propósito de reconocer las actividades de vinculación como generadoras de salud psíquica. Nos propusimos echar luz sobre los procesos de elaboración propios de la población mayor, atendiendo a sus representaciones sobre el proceso de envejecimiento, y a las motivaciones y...

Enfermedades endocrinas en el adulto mayor

Directory of Open Access Journals (Sweden)

B. Carlos García, Dr.

2013-09-01

A pesar de la heterogeneidad, múltiple co morbilidad y escasa literatura en que se incluye adultos mayores, se proponen algunas recomendaciones para el tratamiento individual del paciente diabético anciano, se revisan las particularidades del diagnóstico y tratamiento del híper e hipotiroidismo, algunas ideas en relación al manejo de la osteoporosis en la mujer mayor y el hombre anciano. Finalmente se aborda la dificultad diagnóstica del hipogonadismo tardío con las indicaciones y contra indicaciones del uso de testosterona.

DC/DC converters for integration of double-layer condensers in onboard power supply; DC/DC-Wandler zur Einbindung von Doppelschichtkondensatoren in das Fahrzeugenergiebordnetz

Energy Technology Data Exchange (ETDEWEB)

Polenov, Dieter

2010-01-15

The paper discusses DC/DC converters for integration of double layer condensers into the onboard power system. First, requirements on DC/DC converters are listed and compared on the basis of three exemplary applications. A DC/DC converter concept is developed for decoupling transient high-power loads like electric steering systems. Three different topologies are compared using a specially developed method in order to find the best solution for the given application. In order to establish adequate criteria for selecting the switching frequency and inductivities of storage throttles, the influence of the trottle power change on the switching characteristics of the MOSFETs and on certain ranges of EMP interference emissions is investigated. As methods of optimising the operation of the synchronous rectifiers, parallel connection of Schottky diodes and synchronous rectifiers as well as the variation of the shut-off dead times of synchronous rectifiers were investigated. Further, a concept for converter control was developed in consideration of the intended application and topology. Finally, selected aspects for implementation of the DC/DC converter concept are presented as well as the results of experimental investigations.

Chaos analysis and chaotic EMI suppression of DC-DC converters

CERN Document Server

Zhang, Bo

2014-01-01

Introduces chaos theory, its analytical methods and the means to apply chaos to the switching power supply design DC-DC converters are typical switching systems which have plenty of nonlinear behaviors, such as bifurcation and chaos. The nonlinear behaviors of DC-DC converters have been studied heavily over the past 20 years, yet researchers are still unsure of the practical application of bifurcations and chaos in switching converters. The electromagnetic interference (EMI), which resulted from the high rates of changes of voltage and current, has become a major design criterion in DC-DC co

Solar Decathlon Visitors Guide 2011, National Mall, West Potomac Park, Washington, D.C., September 23 - October 2, 2011 (Brochure)

Energy Technology Data Exchange (ETDEWEB)

2011-09-01

Guide to the student-designed houses, ten contests, exhibits, and workshops of the U.S. Department of Energy 2011 Solar Decathlon, held in Washington, D.C., from September 23 through October 2, 2011. Teams of college students designed and built the solar-powered houses on display here. They represent 13 U.S. states, five countries, and four continents. Now the teams are rising to the challenge by competing in 10 contests over nine days, with the championship trophy on the line. This is their time to shine. The 2011 teams may share a common goal - to design and build the best energy-efficient house powered by the sun - but their strategies are different. One house is made of precast concrete, while another 'dances' in response to its environment. Another house is meant to sit atop a building, proving the sky's the limit for energy innovation. Whatever your idea of sustainable living may be, you are bound to find it at the Solar Decathlon.

Nivel de autotrascendencia en un grupo de adultos mayores mexicanos

Directory of Open Access Journals (Sweden)

Raúl Fernando Guerrero Castañeda

2017-01-01

Full Text Available Introducción: La autotrascendencia es una expansión multidimensional personal, una conexión con los demás, el entorno y/o una entidad superior, está relacionada con el bienestar personal del adulto mayor. Objetivo: Determinar el nivel de autotrascendencia de un grupo de adultos mayores mexicanos. Materiales y Métodos: Estudio descriptivo de corte transversal; realizado en tres centros gerontológicos de Celaya, Guanajuato, México, muestra probabilística aleatoria n=118. Se incluyeron adultos mayores que acudían a los centros gerontológicos, hombres y mujeres, ≥ 60 años. Se utilizó la Escala de Autotrascendencia en español con valor resultante entre 15 y 60 (mayor puntaje = mayor autotrascendencia. Se realizó prueba piloto con 40 adultos mayores con Alpha de Cronbach de 0.80. Análisis estadístico descriptivo para variables categóricas (frecuencias y porcentajes, para variables numéricas: medidas de tendencia central y dispersión. Resultados: Media de Autotrascendencia fue 51.36. Se identificaron con “Encontrando significado en mis creencias espirituales” (85.6% y “Disfrutando mi ritmo de vida” (81.4%; hubo diferencia estadísticamente significativa en la media de Autotrascendencia (p˂0.05 por sexo, siendo mayor el nivel en las mujeres. No hubo diferencia entre grupos de edad. Discusión y Conclusiones: La media de autotrascendencia refleja un nivel alto, en comparación con otros estudios y se reportó entre 75-84 años una media mayor. Los adultos mayores se identifican con características como la religión y el disfrute de la vida. La Escala de Autotrascendencia se puede usar en adultos mayores mexicanos ya que demostró un buen nivel de consistencia interna. Cómo citar este artículo: Guerrero RF, Lara R. Nivel de autotrascendencia en un grupo de adultos mayores mexicanos. Rev Cuid. 2017; 8(1: 1476-87. http://dx.doi.org/10.15649/cuidarte.v8i1.354

Full wave dc-to-dc converter using energy storage transformers

Science.gov (United States)

Moore, E. T.; Wilson, T. G.

1969-01-01

Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

Pulsewidth modulated DC-to-DC power conversion circuits, dynamics, and control designs

CERN Document Server

Choi, Byungcho

2013-01-01

This is the definitive reference for anyone involved in pulsewidth modulated DC-to-DC power conversion Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs provides engineers, researchers, and students in the power electronics field with comprehensive and complete guidance to understanding pulsewidth modulated (PWM) DC-to-DC power converters. Presented in three parts, the book addresses the circuitry and operation of PWM DC-to-DC converters and their dynamic characteristics, along with in-depth discussions of control design of PWM DC-to

Triple voltage dc-to-dc converter and method

Science.gov (United States)

Su, Gui-Jia

2008-08-05

A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

Maltrato en el adulto mayor institucionalizado

OpenAIRE

Eu. Yuly Adams, C.

2012-01-01

El maltrato al adulto mayor es un fenómeno presente tanto en nuestro país como en el extranjero, del que no existen estadísticas claras y actualizadas que permitan evaluar su impacto personal ni social. No obstante, en Chile, en el actual escenario de transición demográfica, se presume su protagonismo. En los establecimientos de larga estadía para adultos mayores, el maltrato, es una situación real y recurrente. Si bien en este ámbito específico las estadísticas son aun más escasas, los me...

Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

Science.gov (United States)

Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

2014-09-09

A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

The performance of the DC motor by the PID controlling PWM DC-DC boost converter

OpenAIRE

Can, Erol; Sayan, Hasan Hüseyin

2017-01-01

This paper presents the PID controlling direct current (DC) to the direct current boost converter feds DC motor which has a 3.68 kW and 240 V of DC voltage input on its characteristics. What is first formed is the boost converter mathematical model at the design stage. Secondly, a mathematical model of the DC motor is created so that the boost converter with the machine can be established and modeled at the Matlab Simulink. The PID controller is considered for arranging a pulse width modulati...

On and off controlled resonant dc-dc power converter

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a resonant DC-DC power converter comprising an input side circuit comprising a positive and a negative input terminal for receipt of an input voltage or current and an output side circuit comprising positive and negative output terminals for supply of a converter...... output voltage and connection to a converter load. The resonant DC-DC power converter further comprises a rectification circuit connected between an output of a resonant network and the output side circuit. The resonant network is configured for alternatingly being charged from the input voltage...... or current and discharged through the rectification circuit by a first controllable switch arrangement in accordance with a first switch control signal. A second controllable switch arrangement of the resonant DC-DC power converter is configured to select a first impedance characteristic of the resonant...

The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

DEFF Research Database (Denmark)

Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

2017-01-01

A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

75 FR 27401 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

Science.gov (United States)

2010-05-17

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes... airworthiness directive (AD) for certain Model DC-9-30, DC-9-40, and DC-9-50 series airplanes. This AD requires... this AD to detect and correct the potential for an arc/spark condition to occur within the fuel boost...

A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

Directory of Open Access Journals (Sweden)

Haojie Wang

2016-07-01

Full Text Available It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC is proposed for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control.

A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

DEFF Research Database (Denmark)

Wang, Haojie; Han, Minxiao; Yan, Wenli

2016-01-01

It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed...... for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load...... changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control....

Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters

Science.gov (United States)

Martinez-Rodrigo, Fernando; Herrero-De Lucas, Luis Carlos; de Pablo, Santiago; Rey-Boue, Alexis B.

2017-01-01

This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results…

Improved Control Strategy for T-type Isolated DC/DC Converters

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Wang, Yanbo

2017-01-01

T-type isolated DC/DC converters have recently attracted attention due to their numerous advantages, including few components, low cost, and symmetrical operation of transformers. This study proposes an improved control strategy for increasing the efficiency of T-type isolated DC/DC converters....... Under the proposed strategy, the primary circulating current flows through the auxiliary switches (metal–oxide–semiconductor field-effect transistors) instead of their body diodes in free-wheeling periods. Such feature can reduce conduction losses, thereby improving the efficiency of T-type isolated DC...

High power density dc/dc converter: Selection of converter topology

Science.gov (United States)

Divan, Deepakraj M.

1990-01-01

The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

Directory of Open Access Journals (Sweden)

Liwen Pan

2016-06-01

Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.

Resocialización en el Adulto Mayor

Directory of Open Access Journals (Sweden)

Zandra Liliana Cabara

2004-11-01

Full Text Available Este artículo plantea un estudio sobre la descripción de métodos de resocialización en el adulto mayor, evidenciando sus potencialidades como auto transformador de su mundo circundante dejando de Iado preconceptos sobre la vejez. Las reflexiones que se plantean en este articulo son producto de un estudio preliminar, don de se aplicó una prueba piloto a tres adultos mayores de diferentes niveles socioculturales pero pertenecientes al mismo estrato económico que se encuentran formando parte de un grupo organizado de atención integral al Adulto Mayor, coordinado por una Fundación Gerontológica en el municipio de Duitama. Se hace un análisis comparativo mediante un método de investigación cualitativa y descriptiva. Restaría, profundizar en la investigación e incluir un estudio comparativo de abuelos con características similares no pertenecientes a grupos organizados.

Prevalencia de trastornos temporomandibulares en el adulto mayor institucionalizado

Directory of Open Access Journals (Sweden)

Zenia Masiel Criado Mora

Full Text Available Introducción: los trastornos temporomandibulares (TTM son una serie de signos y síntomas buco faciales de etiología multifactorial. En Cuba existen varias investigaciones que tratan sobre los TTM %sobre todo en jóvenes dentados% no conociéndose amplias referencias de este tipo de estudio en el adulto mayor. Objetivo: identificar la prevalencia de TTM en los adultos mayores institucionalizados, los signos y síntomas más frecuentes según edad y sexo. Métodos: se realizó un estudio descriptivo transversal en 113 adultos mayores de ambos sexos, institucionalizados en dos hogares de ancianos de la Habana, de marzo a abril de 2012. Se aplicó una encuesta donde se recogió sexo, edad, signos y síntomas. Las manifestaciones clínicas evaluadas fueron: la presencia de dolor muscular, dificultad al movimiento de abertura y cierre, dolor articular, dolor muscular articular, ruidos articulares, limitación de la abertura bucal, limitación de los movimientos de lateralidad y propulsión, desviación de la mandíbula. Resultados: el 40,70 % de los adultos mayores estudiados, presentaron afectación en la articulación temporomandibular. Los ruidos articulares fue el síntoma con mayor predominio en todos los grupos etarios (76,08 %, afectando al 82,35 % de los hombres y al 72,41 % de las mujeres. Seguido por el dolor muscular que se manifestó en el 52,17 % de los afectados, con mayor porcentaje en mujeres (58,62 % que en hombres (41,17 %. La dificultad para realizar los movimientos de abertura y cierre se detectó en el 28,26 % de los afectados con mayor prevalencia en el sexo femenino (34,48 % que en el masculino (17,14 %. Conclusiones. se observó una elevada prevalencia de TTM en los adultos mayores estudiados. Los signos y síntomas más frecuentes por edad y sexo fueron los ruidos articulares y el dolor muscular y la dificultad para realizar los movimientos de abertura y cierre.

RESONANT STEP-DOWN DC-DC POWER CONVERTERS

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a resonant step-down DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage...... charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short......-circuit connection across the galvanic isolation barrier connecting, in a first case, the second negative electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal...

Atmel Microcontroller Based Soft Switched PWM ZVS Full Bridge DC to DC Converter

Directory of Open Access Journals (Sweden)

DEEPAK KUMAR NAYAK

2010-12-01

Full Text Available This paper deals with the simulation and implementation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Later it is rectified using a full wave rectifier. Laboratory model of microcontroller based DC to DC converter is fabricated and tested. The experimental results are compared with the simulation results.

La educación de los adultos mayores en TICs

Directory of Open Access Journals (Sweden)

Boarini, Mauricio Nazareno

2006-01-01

Full Text Available El siguiente trabajo pretende mostrar una propuesta de educación destinada a la capacitación de Adultos Mayores en TICs, teniendo en cuenta el contexto sociocultural actual que originan estas prácticas, su adecuación a los destinatarios y el reconocimiento que las mismas tienen por parte de los Adultos Mayores, quienes enfrentan el desafío de llevar adelante nuevos aprendizajes para sentirse integrados al grupo social con el que conviven. Atendiendo a este propósito, el trabajo se divide en tres partes; en primer lugar se incluyen diferentes proyecciones poblacionales que muestran el crecimiento de la población de Adultos Mayores a nivel mundial, y se caracteriza a la sociedad, donde la integración de las Tecnologías de la Información y la Comunicación cambia las formas de vida. En segundo lugar, se caracteriza al Adulto Mayor como sujeto destinatario de los diferentes cambios que se deben proponer desde el sistema educativo. Por último se describe la propuesta de educación de Adultos Mayores en TICs del Programa Educativo de Adultos Mayores de la Universidad Nacional de Río Cuarto y la valoración de la misma por parte de los alumnos y sociedad en general.

Quasi-Z-Source Half-Bridge DC-DC Converter for Photovoltaic Applications

OpenAIRE

Vinnikov, D; Chub, A; Husev, O; Zaķis, J

2015-01-01

This paper presents a novel quasi-Z-source halfbridge galvanically isolated DC-DC converter intended for the photovoltaic applications. The topology could be envisioned as an alternative to the boost half-bridge DC-DC converter but the benefit of its symmetric structure reduces the threat of transformer saturation due to the dc flux. The proposed converter features the continuous input current and could be used either with one or two input voltage sources.

DC motor operation controlled from a DC/DC power converter in pulse mode with low duty cycle

OpenAIRE

Stefanov, Goce; Kukuseva, Maja; Citkuseva Dimitrovska, Biljana

2016-01-01

In this paper pulse mode of operation of DC motor controlled by DC/DC power converter is analyzed. DC motor operation with time intervals in which the motor operates without output load is of interest. In this mode it is possible the motor to restore energy. Also, in the paper are represented calculations for the amount of the restored energy in the pulse mode operation of the motor for different duty cycles.

BIENESTAR PSICOLÓGICO: ADULTOS MAYORES ACTIVOS A TRAVÉS DEL VOLUNTARIADO

OpenAIRE

FERRADA MUNDACA,LESLIE; ZAVALA GUTIÉRREZ,MERCEDES

2014-01-01

Objetivo: Comparar el nivel de bienestar psicológico de adultos mayores voluntarios del programa "Asesores Seniors" del Servicio Nacional del Adulto Mayor, Región del Bío-Bío, Chile, y adultos mayores no voluntarios, usuarios de un Centro de Salud Familiar de la misma región. Material y método: Corresponde a un estudio descriptivo - comparativo. La población del estudio corresponde a 60 adultos mayores, 30 voluntarios en un programa gubernamental y 30 no voluntarios usuarios de un Centro de S...

Control of the DC-DC Converter used into Energy Generation System

International Nuclear Information System (INIS)

Bizon, Nicu; Oproescu, Mihai

2006-01-01

This paper presents an investigation of the DC-DC Converter controller used into Energy Generation System. The full bridge is used into an Energy Generation System (EGS) as second power interface between the energy source and the high DC bus. The simulation results show that the DC-DC Converter behavior can be improved using a well designed PI control surface. The used Simulink models for the EGS blocks and some design considerations are presented, too. (authors)

Calidad de vida en las personas mayores

OpenAIRE

Sanduvete Chaves, Susana

2004-01-01

El concepto “calidad de vida” adopta una especial relevancia cuando de personas mayores se trata debido a que, a veces, los servicios que reciben están limitados a nivel asistencial, cubriendo sólo las necesidades básicas en lugar de considerar a la persona como un ser integral. Este trabajo pretende ahondar en esta cuestión. Se realizó un estudio bibliométrico para determinar las características de los programas de atención a personas mayores en la actualidad, especificando puntos débi...

Mayor's Firm Hand over N.Y.C. Schools Sparks New Debate

Science.gov (United States)

Archer, Jeff

2004-01-01

This article reports a new debate on mayoral control over New York City schools. Mayoral control of the N.Y.C. schools was at the center of renewed debate, after Mayor Michael R. Bloomberg replaced two members of the city's education policymaking board to ensure enough votes for a controversial plan he backed to end social promotion. The shakeup…

Novel composite resonance DC-DC converter with voltage doubler rectifier

OpenAIRE

Kato, Hisatsugu; Matsuo, Hirohumi; Eguchi, Masaki; Sakamoto, Yukitaka; Nakaishi, Masaki

2009-01-01

This paper deals with a novel composite resonance DC-DC converter with the voltage doubler rectifier, which is developed to be applied to the power conditioner of the photovoltaic generation system. The proposed DC-DC converter has the current and voltage resonance functions. Therefore, the output voltage regulation can be achieved for the large variations of the input voltage and load. Also, this converter has the high power efficiency. The maximum power efficiency 96.1% can be realized.

Ultra-high Efficiency DC-DC Converter using GaN Devices

DEFF Research Database (Denmark)

Ramachandran, Rakesh

2016-01-01

properties of GaN devices can be utilized in power converters to make them more compact and highly efficient. This thesis entitled “Ultra-high Efficiency DC-DC Converter using GaN devices” focuses on achieving ultra-high conversion efficiency in an isolated dc-dc converter by the optimal utilization of Ga...... for many decades. However, the rate of improvement slowed as the silicon power materials asymptotically approached its theoretical bounds. Compared to Si, wideband gap materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) are promising semiconductors for power devices due to their superior...... in this thesis. Efficiency measurements from the hardware prototype of both the topologies are also presented in this thesis. Finally, the bidirectional operation of an optimized isolated dc-dc converter is presented. The optimized converter has achieved an ultra-high efficiency of 98.8% in both directions...

75 FR 61352 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-30, DC-10-30F, DC-10-30F (KC...

Science.gov (United States)

2010-10-05

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10...-13 McDonnell Douglas Corporation: Amendment 39-16448; Docket No. FAA-2010-0553; Directorate.... Applicability (c) This AD applies to McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A...

Sliding-Mode Control of a Charger/Discharger DC/DC Converter for DC-Bus Regulation in Renewable Power Systems

Directory of Open Access Journals (Sweden)

Sergio Ignacio Serna-Garcés

2016-03-01

Full Text Available Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.

Design and Analysis of Two-Phase Boost DC-DC Converter

OpenAIRE

Taufik Taufik; Tadeus Gunawan; Dale Dolan; Makbul Anwari

2010-01-01

Multiphasing of dc-dc converters has been known to give technical and economical benefits to low voltage high power buck regulator modules. A major advantage of multiphasing dc-dc converters is the improvement of input and output performances in the buck converter. From this aspect, a potential use would be in renewable energy where power quality plays an important factor. This paper presents the design of a 2-phase 200W boost converter for battery charging application. Analysis of results fr...

SCM Handbooks for dc-to-dc Converters

Science.gov (United States)

Lee, F.; Mohmoud, M.; Yu, Y.

1984-01-01

Two documents aid in design of control modules for dc-to-dc converters. Features of SCM include: Adaptive stability, power component stress limiting, implementation of various control laws, unified design approach. Analysis and quidelines contained in handbooks enable engineer to design SCM circuit and confidently predict resulting overall performance.

INTERVENCIÓN PSICOLÓGICA EN ADULTOS MAYORES

Directory of Open Access Journals (Sweden)

Ana Fernanda Rodríguez Uribe

2010-01-01

Full Text Available El objetivo de este artículo es plantear una propuesta de intervención psicológica dirigida a adultos mayores institucionalizados y no institucionalizados; para ello se tomó como referencia la situación actual del adulto, los estudios realizados entorno a esta etapa y específicamente lo relacionado con el diseño de programas de intervención, para finalmente exponer la propuesta de intervención psicológica que pretende no solo mejorar la calidad de vida del adulto mayor, sino abarcarlo desde sus diversas áreas de funcionamiento.

75 FR 75872 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

Science.gov (United States)

2010-12-07

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes...: We are adopting a new airworthiness directive (AD) for the McDonnell Douglas Corporation airplanes... to include an airworthiness directive (AD) that would apply to certain McDonnell Douglas Model DC-9...

Specific Intensity Direct Current (DC) Electric Field Improves Neural Stem Cell Migration and Enhances Differentiation towards βIII-Tubulin+ Neurons

Science.gov (United States)

Zhao, Huiping; Steiger, Amanda; Nohner, Mitch; Ye, Hui

2015-01-01

Control of stem cell migration and differentiation is vital for efficient stem cell therapy. Literature reporting electric field–guided migration and differentiation is emerging. However, it is unknown if a field that causes cell migration is also capable of guiding cell differentiation—and the mechanisms for these processes remain unclear. Here, we report that a 115 V/m direct current (DC) electric field can induce directional migration of neural precursor cells (NPCs). Whole cell patching revealed that the cell membrane depolarized in the electric field, and buffering of extracellular calcium via EGTA prevented cell migration under these conditions. Immunocytochemical staining indicated that the same electric intensity could also be used to enhance differentiation and increase the percentage of cell differentiation into neurons, but not astrocytes and oligodendrocytes. The results indicate that DC electric field of this specific intensity is capable of promoting cell directional migration and orchestrating functional differentiation, suggestively mediated by calcium influx during DC field exposure. PMID:26068466

A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

DEFF Research Database (Denmark)

Qin, Zian; Pang, Ying; Wang, Huai

2016-01-01

The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

Actitudes europeos ante el envejecimiento y los personas mayores

Directory of Open Access Journals (Sweden)

ALAN WALKER

1996-01-01

Full Text Available n este artículo se realiza un análisis comparativo de las actitudes ante el envejecimiento y las personas mayores en los doce estados miembros de la unión europea. Está basado en datos originales de encuesta y se centra en la relación entre las personas mayores y los jovenes, la jubilación y las pensiones, los trabajadores de edad y el empleo, la atención social a las personas mayores y la política de la vejez. Por lo tanto, el artículo intenta proporcionar un resumen de las principales dimensiones de las actitudes publicas ante el envejecimiento en la union europea.

LA VIOLENCIA HACIA LA MUJER MAYOR: REVISIÓN BIBLIOGRÁFICA

Directory of Open Access Journals (Sweden)

Montserrat Celdrán

2013-01-01

Full Text Available A pesar de que el maltrato y la negligencia hacia las personas mayores no es una temática desconocida ni a nivel científico ni de la intervención práctica, perspectivas actuales señalan que al resaltar la edad como factor explicativo de la violencia hacia este colectivo, se ha olvidado la perspectiva de género como forma de entender y actuar sobre la violencia hacia las personas mayores. Esta revisión bibliográfica se centra en esta cuestión de género a la hora de detectar e intervenir en la violencia dirigida hacia la mujer mayor. En concreto se analizarán tres ámbitos estudiados a nivel internacional: características del maltrato hacia la mujer mayor, consecuencias de dicho maltrato a nivel de salud y calidad de vida y propuestas de intervención hacia este colectivo. El artículo quiere servir de marco para iniciar estudios a nivel nacional sobre la problemática de las mujeres mayores que sufren violencia de pareja, tema todavía inédito en nuestro entorno.

Active pre-filters for dc/dc Boost regulators

Directory of Open Access Journals (Sweden)

Carlos Andrés Ramos-Paja

2014-05-01

Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.

Laboratory manual for pulse-width modulated DC-DC power converters

CERN Document Server

Kazimierczuk, Marian K

2015-01-01

Designed to complement a range of power electronics study resources, this unique lab manual helps students to gain a deep understanding of the operation, modeling, analysis, design, and performance of pulse-width modulated (PWM) DC-DC power converters.  Exercises focus on three essential areas of power electronics: open-loop power stages; small-signal modeling, design of feedback loops and PWM DC-DC converter control schemes; and semiconductor devices such as silicon, silicon carbide and gallium nitride. Meeting the standards required by industrial employers, the lab manual combines program

A Novel PPFHB Bidirectional DC-DC Converter for Supercapacitor Application

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

2009-01-01

This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase-shift modula......This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase...

Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint

Energy Technology Data Exchange (ETDEWEB)

Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sinha, Mohit [University of Minnesota; Dhople, Sairaj [University of Minnesota; Poon, Jason [University of California at Berkeley

2017-09-01

We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy for switch interleaving of paralleled dc-dc buck converters.

Political Public Relations Campaign for Election of Mayor and Deputy Mayor of Solok Period 2016-2020, Creative Design Coordinator Division

OpenAIRE

Sanjaya, Lovegi David; M.Si, Agus Naryoso; M.Si, Much Yulianto; Gono, Joyo M S; Ayun, Primada Qurrota

2016-01-01

Public relations, as one of the strategies are quite effective for building the image, as well as long-term relationship with the community or public. This strategy is often combined with a political strategy to win a pair of political party candidates, which is the background of the writing of this scientific work ; the intention to won Irzal Ilyas and Alfauzi Bote as pair of political candidates to become mayor and deputy mayor of Solok period 2016-2021. There need to be applied various eff...

La competencia mediática en personas mayores

Directory of Open Access Journals (Sweden)

Isidro Marín Gutiérrez

2013-07-01

Full Text Available Este artículo ha sido realizado gracias al proyecto I+D+i titulado “La competencia en comunicación audiovisual en un entorno digital” (I+D: EDU 2010-21395-C03 financiado por el Ministerio de Ciencia y Tecnología del Gobierno de España. En ella analizamos el pretest que evaluaba la competencia mediática de personas mayores de 60 años de La Rioja y de Huelva. Los resultados arrojados fueron tenidos en cuenta para el proceso de encuestación que se está realizando actualmente en 10 provincias españolas con una muestra de 615 personas mayores de 60 años. En este artículo estudiaremos el estado de la cuestión en torno a las competencias mediáticas de las personas mayores de 60 años.

Incontinencia urinaria en el adulto mayor

Directory of Open Access Journals (Sweden)

Humberto Chiang, Dr.

2018-03-01

Full Text Available Resumen: La incontinencia urinaria (IU es una condición prevalente en la población de adultos mayores, afectando a ambos sexos. Con el envejecimiento de la población será un problema de salud de cada vez mayor relevancia. Su patogenia es compleja y multifactorial, por lo que es fundamental conocer los aspectos fisiopatológicos subyacentes para realizar un adecuado diagnóstico en base a la historia clínica, examen físico y exámenes complementarios solicitados de manera racional. El tratamiento de la IU para adultos mayores no difiere mayormente de los tratamientos utilizados en población más joven. Sin embargo, debe hacerse particular énfasis en identificar comorbilidades, fármacos, trastornos neurológicos y psiquiátricos que puedan estar contribuyendo a la IU. Debe sacarse el máximo provecho del manejo conservador, teniendo consideraciones especiales con el uso de algunos fármacos e indicando cuidadosamente tratamiento quirúrgico a pacientes seleccionados. Summary: Urinary incontinence (UI is a prevalent condition in the population of elderly adults, affecting both sexes. With the aging of the population it will be a health problem of increasing relevance. Its pathogenesis is complex and multifactorial, so it is essential to know the underlying pathophysiological aspects in order to make an adequate diagnosis based on the clinical history, physical examination and complementary tests requested in a rational manner. The treatment of UI for elderly adults does not differ much from the treatment of younger population. However, particular emphasis should be placed on identifying comorbidities, medications, neurological and psychiatric disorders that may be contributing to the UI. Full advantange of conservative management should be taken, having special considerations with the use of some drugs and carefully indicating surgical treatment to selected patients. Palabras clave: Incontinencia urinaria, adulto mayor, envejecimiento

CISH is induced during DC development and regulates DC-mediated CTL activation.

Science.gov (United States)

Miah, Mohammad Alam; Yoon, Cheol-Hee; Kim, Joonoh; Jang, Jinah; Seong, Young-Rim; Bae, Yong-Soo

2012-01-01

The cytokine inducible SH2-domain protein (CISH) is a well-known STAT5 target gene, but its role in the immune system remains uncertain. In this study, we found that CISH is predominantly induced during dendritic cell (DC) development from mouse bone marrow (BM) cells and plays a crucial role in type 1 DC development and DC-mediated CTL activation. CISH knockdown reduced the expression of MHC class I, co-stimulatory molecules and pro-inflammatory cytokines in BMDCs. Meanwhile, the DC yield was markedly enhanced by CISH knockdown via cell-cycle activation and reduction of cell apoptosis. Down-regulation of cell proliferation at the later stage of DC development was found to be associated with CISH-mediated negative feedback regulation of STAT5 activation. In T-cell immunity, OT-1 T-cell proliferation was significantly reduced by CISH knockdown in DCs, whereas OT-2 T-cell proliferation was not affected by CISH knockdown. CTLs generated by DC vaccination were also markedly reduced by CISH knockdown, followed by significant impairment of DC-based tumor immunotherapy. Taken together, our data suggest that CISH expression at the later stage of DC development triggers the shutdown of DC progenitor cell proliferation and facilitates DC differentiation into a potent stimulator of CTLs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Bidirectional Multi-Port DC-DC Converter Integrating Voltage Equalizer

DEFF Research Database (Denmark)

Chen, Jianfei; Hou, Shiying; Deng, Fujin

2015-01-01

A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalize...... battery modules with different voltages. Simulation results has shown the feasibility of the proposed converter.......A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalized...

Prevalencia de depresión mayor en adultos mayores atendidos ambulatoriamente en un hospital de lima metropolitana

Directory of Open Access Journals (Sweden)

Magnolia Matutti Rosas

2016-12-01

Full Text Available RESUMEN: El objetivo del presente estudio es describir, analizar prevalencia y factores de riesgo predictivo asociado a depresión mayor, en adultos mayores atendidos en consulta ambulatoria de psiquiatría de un hospital, y en un grupo de adultos mayores no asegurados. Se evaluó a 79 adultos mayores no asegurados de una comunidad del Callao y a 221 pacientes con depresión y depresión comórbida, atendidos en consulta ambulatoria de psiquiatría. Se aplicó una encuesta de consumo de medicamentos. Los resultados indican que los factores demográficos son independientes de depresión en ambos grupos (OR=1.792, IC95%=0.573-5.606, edad; OR=1.123, IC95%=0.435-4.768, sexo; OR=2.344, IC95%=0.325-16.928, autopercepción de salud; OR=1.905, IC95%=0.642-2.434, depresión; OR=1. 250, IC95%=0.642-2.434, consumo de medicamentos; OR=1.260, IC95%=0.763-2.084, número de enfermedad. Las personas no aseguradas evidencian depresión comórbida con diabetes mellitus, HTA, Artrosis, encontrando mayor frecuencia en mujeres de 60 a 75 años que en mujeres de 76 años a más. ABSTRACT: Objective: To describe, analyze prevalence and predictive risk factors associated with major depression, seniors attended outpatient psychiatric, and uninsured. Material and Methods: 79 elderly uninsured community surrounding Callao to EsSalud, Survey of Drug Consumption applies; and 221 patients with depression and comorbid depression, diagnosed in Psychiatry Clinic. It was used, the Drug Consumption Survey. Results: Demographic factors are independent of depression in both groups (OR = 1.792, 95%CI = 0.573-5.606, age; OR = 1.123, 95%CI = 0.435-4.768, sex; OR = 2.344, 95%CI = 0.325-16.928, health self-perception; OR = 1,905, 95%CI = 0.642 -2.434, depression;, OR = 1. 250, 95%CI = 0.642-2.434, drug use; OR = 1260, 95%CI = 0.763-2.084, disease number. Uninsured comorbid with depression show DM, hypertension, osteoarthritis, and women age 60-75 It is more frequent than in Group 76

A Current-Fed Isolated Bidirectional DC-DC Converter

DEFF Research Database (Denmark)

Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

2017-01-01

This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...

Bi-Directional DC-DC Converter for PHEV Applications

Energy Technology Data Exchange (ETDEWEB)

Abas Goodarzi

2011-01-31

Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

Factores asociados al maltrato del adulto mayor de Antioquia, 2012

OpenAIRE

Sara M. Cano; María O. Garzón; Ángela M. Segura; Doris Cardona

2015-01-01

Objetivo: determinar los factores asociados al maltrato del adulto mayor del departamento de Antioquia en el año 2012. Metodología: mediante estudio descriptivo transversal, se caracterizaron los factores demográficos, económicos y de salud mental de la población adulta mayor de Antioquia para el año 2012, con el fin de aportar al análisis de la situación de salud y condiciones de vida del adulto mayor. El estudio se basó en los resultados del instrumento aplicado por la Universidad ces a 4.2...

Determination of input/output characteristics of full-bridge AC/DC/DC converter for arc welding

OpenAIRE

Stefanov, Goce; Karadzinov, Ljupco; Sarac, Vasilija; Cingoski, Vlatko; Gelev, Saso

2016-01-01

This paper describes the design and practical implementation of AC/DC/DC converter in mode of arc welding. An analysis of the operation of AC/DC/DC converter and its input/output characteristics are determined with computer simulations. The practical part is consisted of AC/DC/DC converter prototype for arc welding with output power of 3 kW and switching frequency of 64 kHz. The operation of AC/DC/DC converter is validated with experimental measurements.

ITAR Free Commercial-of-the-Shelf DC/DC Converter

Science.gov (United States)

Denzinger, Wolfgang; Hintze, Thomas

2014-08-01

A commercial-of-the-shelf (COTS) DC/DC converter for digital space equipment has been developed by ASP under ESA contract with special emphasis on low cost, no use of ITAR listed EEE parts like Mosfets, minimum number of rad-hard digital IC's and a design tolerance against single event effects by appropriate filtering. However, the intention to qualify this discrete converter design for a low cost FM series production was difficult due to the high up-sceening cost of EEE-parts with one lot guarantee and minimum-by. To overcome this problem, in a next step a redesign of the DC/DC converter was performed with all semiconductors like bipolar transistors, rectifiers and zener diodes packaged into hybrids. With this approach it was possible to buy a high number of less expensive wafers or dies from one lot, to perform a lot acceptance test and to integrate the dies into hybrid packages with further up- screening for FM use. The semiconductors have been packaged into three signal hybrids with 44 pins and one power hybrid with 24 pins for the dissipating transistors and rectifiers. The design of the hybrids is such, that all integrated semiconductors can be tested individually. The qualification of four EQM DC/DC converters with different combinations of output voltages has been successfully performed and two FM's have been manufactured and tested.

Performance of 22.4-kW nonlaminated-frame dc series motor with chopper controller. [a dc to dc voltage converter

Science.gov (United States)

Schwab, J. R.

1979-01-01

Performance data obtained through experimental testing of a 22.4 kW traction motor using two types of excitation are presented. Ripple free dc from a motor-generator set for baseline data and pulse width modulated dc as supplied by a battery pack and chopper controller were used for excitation. For the same average values of input voltage and current, the motor power output was independent of the type of excitation. However, at the same speeds, the motor efficiency at low power output (corresponding to low duty cycle of the controller) was 5 to 10 percentage points lower on chopped dc than on ripple free dc. The chopped dc locked-rotor torque was approximately 1 to 3 percent greater than the ripple free dc torque for the same average current.

Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

CSIR Research Space (South Africa)

Grobler, Inus

2013-09-01

Full Text Available . The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised...

A New Sliding Mode Controller for DC/DC Converters in Photovoltaic Systems

Directory of Open Access Journals (Sweden)

M. Sarvi

2013-01-01

Full Text Available DC/DC converters are widely used in many industrial and electrical systems. As DC/DC converters are nonlinear and time-variant systems, the application of linear control techniques for the control of these converters is not suitable. In this paper, a new sliding mode controller is proposed as the indirect control method and compared to a simple direct control method in order to control a buck converter in photovoltaic applications. The solar arrays are dependent power sources with nonlinear voltage-current characteristics under different environmental conditions (insolation and temperature. From this point of view, the DC/DC converter is particularly suitable for the application of the sliding mode control in photovoltaic application, because of its controllable states. Simulations are performed in Matlab/Simulink software. The simulation results are presented for a step change in reference voltage and input voltage as well as step load variations. The simulations results of proposed method are compared with the conventional PID controller. The results show the good performance of the proposed sliding mode controller. The proposed method can be used for the other DC/DC converter.

Adultos mayores cuidadores: sobrecarga y dimensión afectiva

Directory of Open Access Journals (Sweden)

Serrana Banchero

2017-05-01

Full Text Available Este trabajo plantea la relación entre la sobrecarga del cuidador y la dimensión afectiva del cuidado en personas mayores cuidadoras. En la actualidad el cuidado es entendido como una problemática social pública, y por lo tanto objeto de políticas públicas. Uruguay es un país envejecido debido a los cambios socio-demográficos que han acontecido por lo que han aumentado las situaciones de dependencia y las demandas de cuidados. De este modo, las personas mayores no solo son receptores sino también proveedores de cuidados. El cuidado implica la dimensión material, económica y afectiva, y los cuidadores como consecuencia de su tarea de cuidar, pueden experimentar el síndrome de sobrecarga del cuidador. Se trata de un diseño cuali-cuantitativo y consiste en un estudio de caso utilizando entrevistas individuales con aplicación de instrumentos según la categorización de la muestra finalista que fue Personas Mayores Cuidadoras y no Cuidadoras. Se analizará la variable sobrecarga del cuidador con las características de la relación cuidador-cuidado. La muestra es finalista y se constituyó por 74 personas mayores usuarios regulares del Subprograma Adultos Mayores del Programa Apex-Cerro (UdelaR de la ciudad de Montevideo, Uruguay. Los resultados mostraron que aparece una visión totalizante del cuidado, así como relatos autorreferenciales. El 29,7% son personas mayores cuidadoras, de los cuales el 15,7% presentan el síndrome de sobrecarga del cuidador (siendo todas mujeres y la edad mediana de 65,5 años. En el análisis de la dimensión afectiva del cuidado se observan características de un tipo de vínculo co-dependiente entre el cuidador y el cuidado.

Very High Frequency Half Bridge DC/DC Converter

DEFF Research Database (Denmark)

Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

2014-01-01

This paper presents the first, off chip, class DE (resonant half bridge) converter working in the Very High Frequency (VHF) range. The benefits of using half bridge circuits both in the inverter and rectifier part of a VHF resonant dc/dc converter are analyzed and design equations for all...

Sheppard-Taylor Isolated High Boost DC-DC Converter

DEFF Research Database (Denmark)

Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

2017-01-01

This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can...

Political Leadership in Issue Networks : How Mayors Rule Their World?

NARCIS (Netherlands)

Denters, Sebastianus A.H.; Steyvers, Kristof; Klok, Pieter-Jan; Cermak, Daniel; Heinelt, Hubert; Magnier, Annick; Cabria, Marcello; Reynaert, Herwig

2018-01-01

In his controversial book If Mayors Ruled the World, US political theorist Benjamin Barber argued that mayors can and do play a major role in solving today’s grand societal challenges in domains like social inclusion and poverty, climate change and sustainability and safety and public order. It is

Resiliencia en cuidadores familiares de personas mayores dependientes

Directory of Open Access Journals (Sweden)

María Crespo

2015-01-01

Full Text Available El presente trabajo analiza la distribución de los niveles de resiliencia en cuidadores no profesionales (familiares de personas mayores dependientes, y explora las características que poseen los cuidadores altamente resilientes. Para ello se administró la escala CD-RISC a una muestra de 111 cuidadores. En función de las puntuaciones obtenidas, se distinguieron dos grupos: alta vs. moderada o baja resiliencia. Se analizaron las diferencias entre ambos grupos en las diversas variables que afectan al estrés del cuidador. Aunque hubo diferencias en el estado cognitivo del receptor de cuidado, las mayores diferencias se obtuvieron en las denominadas variables mediadoras, observando en los cuidadores con alta resiliencia mayores puntuaciones en: satisfacción con el apoyo social recibido, autoeficacia para controlar los pensamientos negativos, autoestima, autocuidado y extraversión; y siendo estas diferencias estadísticamente significativas. Asimismo los cuidadores altamente resilientes tendieron a manifestar una menor preocupación por los problemas del mayor, y presentaron menores niveles de sintomatología depresiva y ansiosa. Este estudio pone de manifiesto la importancia de la resiliencia como factor de protección en el ámbito del estrés crónico, incorporando aspectos positivos de la adaptación a los modelos teóricos de cuidado, los cuales tradicionalmente se han venido centrando en el desarrollo de sintomatología.

A DC-DC Conversion Powering Scheme for the CMS Phase-1 Pixel Upgrade

CERN Document Server

Feld, Lutz Werner; Marcel Friedrichs; Richard Hensch; Karpinski, Waclaw; Klein, Katja; Sammet, Jan Domenik; Wlochal, Michael

2012-01-01

The powering scheme of the CMS pixel detector will be described, and the performance of prototype DC-DC buck converters will be presented, including power efficiency, system tests with DC-DC converters and pixel modules, thermal management, reliability at low temperature, and studies of potential frequency locking betwe...

Alexitimia, resiliencia y creencias paranormales en personas mayores en un centro institucionalizado

Directory of Open Access Journals (Sweden)

Inmaculada Méndez

2015-08-01

Full Text Available La alexitimia hace referencia a la dificultad para comprender e identificar los propios sentimientos y los de los demás. El proceso de adaptación a un centro residencial es una de las situaciones estresantes a las que puede enfrentarse la persona mayor. Para poder sobreponerse ante dichas situaciones es fundamental la capacidad de resiliencia e incluso existen personas que buscan apoyo en la religiosidad o en las creencias en lo paranormal. En este trabajo se estudió la relación entre aleximitia, resiliencia y creencias paranormales en un grupo de 35 personas mayores (21 mujeres con edades entre 66 y 95 años de un centro institucionalizado. Se administraron la escala TAS-20 para la evaluación de la alexitimia, la Escala de Resiliencia CD-RISC y la Escala Mejorada de Creencias Paranormales. Entre los principales resultados cabe destacar que los sujetos con mayores Dificultades para identificar sentimientos son los que presentaban un menor Control personal; los sujetos con mayores Dificultades para identificar sentimientos son los que menor creencia poseían de las Formas de vida extraordinaria y los sujetos con mayor capacidad de Control Personal son los que mayor creencia tenían de las Formas de vida extraordinaria. Se discuten las aplicaciones que los profesionales pueden poner en marcha en centros institucionalizados de personas mayores.

Study on the Control Algorithm of Two-Stage DC-DC Converter for Electric Vehicles

Directory of Open Access Journals (Sweden)

Changhao Piao

2014-01-01

Full Text Available The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM controller and double-integral sliding mode (DISM controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error.

Un estudio exploratorio de capacidades emocionales en adultos mayores

Directory of Open Access Journals (Sweden)

Zoe S. Bello Dávila

2012-01-01

Full Text Available Abstract The study of the emotional world of the elderly is a fundamental requisite for guaranteeing the well-being and health of this group. The objective of this research paper was to characterize a group of elderly people according to their motional capabilities. The group consisted of 122 elderly persons: 107 female, 15 male. All attendants participated in a “Círculo de Abuelos” (Circle of Grandparents. The study was descriptive, it sought to gather information about the responses of older adults in situations of emotional content by completing a questionnaire. The results provided a profile of capacities where areas of strength and weakness are clearly distinguished. Selfconfidence and the possibility of fulfilling projects are among the strengths while the weaknesses are found in interpersonal or intrapersonal managing of emotions. These results have led to a better understanding of the emotional world of the elderly and guide future educational activities. Resumen El estudio del mundo emocional de los adultos mayores es un requisito fundamental para garantizar el estado de bienestar y salud de los mismos. El presente artículo de investigación se fijó como objetivo caracterizar a un grupo de ancianos, en función de sus capacidades emocionales. Los participantes fueron 122 ancianos, en concreto 107 mujeres y 15 hombres, que asisten a un “Círculo de Abuelos”. El estudio fue de tipo descriptivo, pues pretendió recoger información acerca de las respuestas de los adultos mayores ante situaciones de contenido emocional que se exploran por medio de un cuestionario elaborado al efecto. Los resultados ofrecen un perfil de capacidades en que la autoconfianza y la posibilidad de elaborar proyectos se erigen como fortalezas, mientras que las debilidades se expresan en las dificultades para el manejo emocional tanto a nivel intra como interpersonal. Estos resultados han permitido lograr una mejor comprensión del mundo emocional del

Regulation of DC development and DC-mediated T-cell immunity via CISH

OpenAIRE

Miah, Mohammad Alam; Bae, Yong-Soo

2013-01-01

Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

Regulation of DC development and DC-mediated T-cell immunity via CISH.

Science.gov (United States)

Miah, Mohammad Alam; Bae, Yong-Soo

2013-03-01

Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

Las personas mayores y su salud: situación actual

OpenAIRE

P. Ramos Cordero; J.A. Pinto Fontanillo

2015-01-01

El envejecimiento de la población es un fenómeno que se está produciendo en todos los países desarrollados. España es el país de Europa con una mayor esperanza de vida y el segundo país a nivel mundial tras Japón. La previsión de este envejecimiento es que se mantenga una proyección constante y que afecte ponderalmente tanto al grupo de los mayores de 65 como al grupo de los mayores de 80, lo que se viene conociendo como el envejecimiento del envejecimiento o sobreenvejecimiento de la poblaci...

Model Prediksi Kebutuhan Darah untuk Penderita Talasemia Mayor

Directory of Open Access Journals (Sweden)

Dwi Sarwani Sri Rejeki

2014-02-01

Full Text Available Pada dua tahun pertama kehidupan penderita talasemia mayor, umumnya menderita anemia dan membutuhkan tranfusi darah. Penelitian ini bertujuan membuat model prediksi kebutuhan darah bagi penderita talasemia mayor. Penelitian observasional dengan desain studi pendekatan potong lintang ini dilakukan pada sampel 79 penderita talasemia mayor yang melakukan transfusi rutin minimal satu bulan satu kali di Rumah Sakit Umum Banyumas, selama tahun 2012. Analisis regresi linier ganda digunakan untuk membuat model prediksi. Hasil penelitian menunjukkan bahwa 80,7% kebutuhan darah penderia talasemia mayor dijelaskan oleh variabel usia, berat badan, dan kadar hemoglobin sedangkan 19,3% dijelaskan oleh sebab-sebab yang lain. Rumus prediksi menyatakan setiap kenaikan usia 1 tahun maka kebutuhan darah akan bertambah sebanyak 0,816 mililiter dan setiap kenaikan 1 kilogram berat badan maka kebutuhan darah akan bertambah 13,4 mililiter serta apabila kadar hemoglobin mengalami penurunan 1 g/dL maka kebutuhan darah akan bertambah sebesar 81 mililiter. Patients with thalassemia major usually present within the first two years of life with severe anemia, need red blood cell transfusion. The objective of this study was to create a prediction model of blood transfusion need for patients with thalassemia mayor. This type of research was observational with cross sectional design. Samples are 79 patients with thalassemia major who perform routine transfusion at least once in a month at Banyumas hospital in 2012. Multiple linier regression analysis was used to create the model. The results showed that 80.7% blood requirements can be explained by variables of weight, haemoglobin level and age, while 19.3% is explained by other causes. Prediction formula states every increment of one year in age, the need for blood will increase by 0.816 millilitres and every increment of one kilogram of body weight, the need for blood will increase 13.4 millilitres, and when the haemoglobin

Controlling DC-DC converters by chaos-based pulse width modulation to reduce EMI

International Nuclear Information System (INIS)

Li Hong; Zhang Bo; Li Zhong; Halang, Wolfgang A.; Chen Guanrong

2009-01-01

In this paper, periodic and chaotic behaviors of DC-DC converters under certain parametric conditions are simulated, experimentally verified, and analyzed. Motivated by the work of J.H.B. Deane and D.C. Hamill in 1996, where chaotic phenomena are useful in suppressing electromagnetic interference (EMI) by adjusting the parameters of the DC-DC converter and making it operate in chaos, a chaos-based pulse width modulation (CPWM) is proposed to distribute the harmonics of the DC-DC converters continuously and evenly over a wide frequency range, thereby reducing the EMI. The output waves and spectral properties of the EMI are simulated and analyzed as the carrier frequency or amplitude changes with regard to different chaotic maps. Simulation and experimental results are given to illustrate the effectiveness of the proposed CPWM, which provides a good example of applying chaos theory in engineering practice.

The Mayor's Influence in Urban School Desegregation

Science.gov (United States)

Dunaway, David King; Beckum, Leonard Charles

1977-01-01

There are five primary areas in which mayors exert visible and invisible influence--appointments, decision-making, public statements, coordination of resources, and provision of basic services. (Author/IRT)

Council Appointed Mayors in Spain: Effects on Local Democracy

Directory of Open Access Journals (Sweden)

María Jesús García García

2017-03-01

Full Text Available This paper deals with the influence of having council appointed mayors on local governments. Five elements of local government systems are considered: the electoral system and its influence on the political composition of the local government; the local government structure and the distribution of functions and powers between mayor and council; the role of political parties; scrutiny of the executive and accountability; and citizen participation. This analysis highlights the effect that a council appointed mayor system has in terms of accountability and legitimacy, transparency and efficiency. KEYWORDS Local government systems, directly elected mayors, local governance, council appointed mayors, Local Government Structure; Political Parties; Citizen Participation; Accountability. El presente artículo toma en consideración los efectos que el sistema de elección del Alcalde tiene sobre la democracia local, basándose en la consideración cinco aspectos: el sistema electoral y su influencia en la composición política de las administraciones locales; la estructura de la administración local y la distribución de funciones entre los alcaldes y el pleno municipal; el papel de los partidos políticos; los mecanismos de control del ejecutivo local y la participación ciudadana. El estudio subraya especialmente la incidencia que el sistema de elección del alcalde por los concejales tiene en relación con los principios de responsabilidad, legitimidad, transparencia y eficiencia de la gestión local. PALABRAS CLAVE Gobierno local, elección directa de los alcaldes, elección indirecta de los alcaldes, estructura del gobierno local, partidos políticos, participación ciudadana, responsabilidad política.

VOLUNTARIADO DE MAYORES: EJEMPLO DE ENVEJECIMIENTO PARTICIPATIVO Y SATISFACTORIO

Directory of Open Access Journals (Sweden)

María Silveria Agulló Tomás

2002-01-01

Full Text Available El objetivo general de este trabajo estriba en desarrollar el tema del voluntariado de mayores como un claro ejemplo de envejecimiento participativo y saludable. En la primera parte se definen los conceptos utilizados y se refleja el «envejecimiento activo» como expresión de una necesidad social más que sólo una tendencia en boga. La participación social de los mayores es destacada como interés prioritario tanto desde las instituciones políticas como socio-económicas. En la segunda, se ofrecen algunos datos e informaciones que ayudan a dibujar una panorámica internacional sobre la situación de los mayores como voluntarios. En la tercera se desarrollan las distintas actividades, tipología, opiniones y vivencias de voluntarios mayores en nuestro contexto español. Al final, entre otras conclusiones y propuestas, se subraya la relevancia de continuar y hacer realidad un «envejecimiento participativo», pero, eso sí, evitando el derrumbe hacia la «explotación» humana para construir una vejez más saludable y justa acorde con los principios básicos de toda sociedad democrática.

Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

Directory of Open Access Journals (Sweden)

Sreenivasappa Veeranna Bhupasandra

2010-01-01

Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

Analysis of high voltage step-up nonisolated DC-DC boost converters

Science.gov (United States)

Alisson Alencar Freitas, Antônio; Lessa Tofoli, Fernando; Junior, Edilson Mineiro Sá; Daher, Sergio; Antunes, Fernando Luiz Marcelo

2016-05-01

A high voltage step-up nonisolated DC-DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC-DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions.

Programa Centros Diurnos del Adulto Mayor: recomendaciones para mejorar su funcionamiento

Directory of Open Access Journals (Sweden)

Alejandra-Ximena Araya

Full Text Available Resumen: Introducción: Chile se ha transformado en un país que continuará envejeciendo a un ritmo acelerado. Una de las piezas claves de la Política Integral de Envejecimiento Positivo para Chile es el desarrollo de centros de día para personas mayores (CDPM dirigidos al cuidado de ancianos con dependencia leve. Objetivo: Conocer la percepción que tiene un grupo de personas mayores, sus cuidadores y profesionales de su participación en un CDPM con el propósito de diseñar recomendaciones para mejorar este nuevo tipo de servicio geriátrico instaurado en el país. Metodología: Estudio descriptivo cualitativo realizado con 30 participantes a través de cuatro grupos focales: dos en personas mayores (n = 12, uno con cuidadores (n = 8 y uno con profesionales del centro (n = 10. El análisis de contenido se realizó según Kripperdorff y se cumplieron los criterios de rigor según Guba y Lincoln. Resultados: Se identificaron dos categorías comprensivas principales: 1 percepción de beneficios para las personas mayores: mejoría de la funcionalidad, aumento del bienestar y mayor inserción social y 2 recomendaciones de mejora del CDPM: criterios de ingreso inclusivo, flexibilidad y diversidad en actividades estipuladas y mejoras en el egreso. Conclusiones: Las personas mayores, sus cuidadores y los profesionales que los atienden coinciden en señalar que la asistencia de las personas mayores a este tipo de servicio les reporta beneficios en su funcionalidad, bienestar e inserción social. Este estudio contribuye a ampliar el entendimiento de los resultados en los usuarios de los CDPM, reportando una experiencia en un contexto social particular.

Common mode noise in three-level DC-DC converters

CSIR Research Space (South Africa)

Grobler, Inus

2009-09-01

Full Text Available that three-level buck DC-DC converters in general generate much lower common mode currents than conventional two-level buck converters. Further, reductions in common mode currents are achieved by using the improved three-level topologies that have been...

Estudio comparativo de alexitimia en personas institucionalizadas versus aula de mayores

Directory of Open Access Journals (Sweden)

Julia García-Sevilla

2016-04-01

Full Text Available La experiencia y regulación de las emociones son aspectos que están adquiriendo mayor importancia a la hora de entender y fomentar el bienestar y la calidad de vida de las personas mayores. El objetivo del presente estudio ha sido llevar a cabo un estudio comparativo de la alexitimia en usuarios pertenecientes a un centro institucionalizado de personas mayores y alumnos matriculados en el aula de mayores. Los participantes del estudio fueron 43 personas institucionalizadas y 48 personas pertenecientes al aula de mayores con una media de edad de 69.30 años y una desviación típica de 66.50. El instrumento utilizado fue la versión adaptada del TAS-20. Los resultados mostraron que las personas institucionalizadas puntuaban más alto en la dificultad para identificar sentimientos, dificultad para describir sentimientos así como en el patrón de pensamiento orientado a lo externo. El sexo fue indiferente en la dificultad para identificar sentimientos, en la dificultad para describir sentimientos así como en el patrón orientado a lo externo. En cuanto a la edad, se encontró una relación con la dificultad para identificar sentimientos y el patrón de pensamiento orientado a lo externo. El estudio permite concluir que la alexitimia se ve influida por el hecho de que la persona mayor se encuentre en un centro institucionalizado.

Analysis and Design of Bi-Directional DC-DC Converter in the Extended Run Time DC UPS System Based on Fuel Cell and Supercapacitor

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2009-01-01

Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The deli......Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes...

DC-DC power converter research for Orbiter/Station power exchange

Science.gov (United States)

Ehsani, M.

1993-01-01

This project was to produce innovative DC-DC power converter concepts which are appropriate for the power exchange between the Orbiter and the Space Station Freedom (SSF). The new converters must interface three regulated power buses on SSF, which are at different voltages, with three fuel cell power buses on the Orbiter which can be at different voltages and should be tracked independently. Power exchange is to be bi-directional between the SSF and the Orbiter. The new converters must satisfy the above operational requirements with better weight, volume, efficiency, and reliability than is available from the present conventional technology. Two families of zero current DC-DC converters were developed and successfully adapted to this application. Most of the converters developed are new and are presented.

Dr Stanislaw Huskowski, Mayor of Wroclaw, Poland

CERN Multimedia

Patrice Loïez

2002-01-01

Dr Stanislaw Huskowski, Mayor of Wroclaw, Poland visiting the ATLAS magnet assembly hall, building 180 with Mr Carlo Lamprecht, State Councillor, Dr Stanislaw Huskowski and Dr Peter Jenni, ATLAS Spokesperson

propiedades psicométricas en adultos mayores

Directory of Open Access Journals (Sweden)

Armando Rivera-Ledesma

2013-01-01

Full Text Available La presente investigación propone la adaptación al español y validación de la Escala de Soporte Social (ESS-AM de Tagaya, Okuno, Tamura y Davis (2000, conducida en cuatro muestras independientes de adultos mayores de la Ciudad de México. La escala, de ocho reactivos, mide la percepción de apoyo social mediante un solo factor que explica el 60,7% de la varianza, con una consistencia interna a de 0,84 y correlaciones negativas significativas con la variable soledad. Con base en ello, se concluye que la ESS-AM es un instrumento confiable, útil y sencillo en funciones de tamizaje para evaluar si el adulto mayor cuenta con adecuados niveles de apoyo social percibido.

Prevalencia de la dependencia funcional en personas mayores

OpenAIRE

Gázquez Linares, José Jesús; Pérez Fuentes, Mª del Carmen; Mercader Rubio, Isabel; Molero Jurado, Mª del Mar

2011-01-01

La consecuencia más inmediata del envejecimiento de la población actual, es el incremento de la dependencia. Así, el objetivo de este trabajo, es dar a conocer la prevalencia del nivel de dependencia para las actividades básicas e instrumentales en la población mayor de 60 años, en función del género, estado civil y la edad, seleccionando una muestra total de 1.222 personas. El nivel de dependencia es mayor entre las mujeres para casi todas las actividades básicas, siendo también las personas...

Sliding-mode control of single input multiple output DC-DC converter

Science.gov (United States)

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Funcionalidad y grado de dependencia en los adultos mayores institucionalizados en centros de bienestar

Directory of Open Access Journals (Sweden)

Elveny Laguado Jaimes

Full Text Available RESUMEN Introducción: La funcionalidad en el adulto mayor constituye un eje principal para los programas orientados a fortalecer el envejecimiento activo; ante el incremento de este grupo poblacional, las enfermedades como factor que limita la capacidad física, mental y social requieren acciones de control que disminuyan la dependencia que contribuye a un deterioro mayor. Objetivo: Determinar la funcionalidad y grado de dependencia en el adulto mayor institucionalizado como información básica para el diseño de un programa de intervención específica. Metodología: estudio descriptivo retrospectivo con una muestra de 60 adultos mayores institucionalizados y seleccionados por muestreo no probabilístico. Resultados: predomina el rango de edad de 75-84 años, un 26,66% de 60 adultos mayores y el género masculino con mayor frecuencia (53,33%. Por lo que respecta a la escolaridad, el 53,3% estudiaron primaria. Contacto familiar con la familia, el 70%; tiempo de institucionalización de los adultos mayores, el mayor tiempo (55% de 1 a 5 años. Predominan los problemas cardiovasculares en el 34% de los adultos mayores. Valoración funcional: predomina el género masculino con dependencia leve (26,66% y como independiente un 25% del género femenino. La valoración del grado de autonomía en el género masculino evidencia un grado de autonomía 1, con un 30% con respecto al género femenino, que tiene un grado de autonomía 3, con el 16,66%, sin significación estadística. Conclusiones: Se observa el predominio del género masculino en los adultos mayores institucionalizados y con dependencia leve, y al contrario en las mujeres, donde la frecuencia de independencia es mayor. En la autonomía predomina un grado mayor en los hombres que en las mujeres.

Significado de ser docente para el adulto mayor sanfernandino

OpenAIRE

Martina, Martha; Santos, Gladys; Lema, Julia

2013-01-01

Objetivos: Comprender el significado de ser docente para el adulto mayor de la Facultad de Medicina de San Marcos y describir las motivaciones que determinan, de alguna forma, su decisión de postergar su retiro, no obstante haber cumplido con los requisitos legales para la jubilación. Diseño: Estudio de caso cualitativo. Institución: Facultad de Medicina, UNMSM. Participantes: Docentes adulto mayores de la Facultad de Medicina. Intervenciones: Entrevista a profundidad. Principales medidas de ...

Y-Source Boost DC/DC Converter for Distributed Generation

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede

2015-01-01

This paper introduces a versatile Y-source boost dc/dc converter intended for distributed power generation, where high gain is often demanded. The proposed converter uses a Y-source impedance network realized with a tightly coupled three-winding inductor for high voltage boosting that is presently...

Redes sociales y mujeres mayores

OpenAIRE

Fernández Campomanes, María

2012-01-01

Estudio de carácter cualitativo sobre la influencia de las redes sociales en la mejora de la calidad de vida de las mujeres mayores, que responden al perfil de mujeres de más de 55 años de edad, cuidadoras y cuyo acceso a las TIC no guarda relación con el empleo ni con el ámbito académico.

SUBCONTRACT REPORT: DC-DC Converter for Fuel Cell and Hybrid Vehicles

Energy Technology Data Exchange (ETDEWEB)

Marlino, Laura D [ORNL; Zhu, Lizhi [Ballard Power Systems/Siemens VDO

2007-07-01

The goal of this project is to develop and fabricate a 5kW dc-dc converter with a baseline 14V output capability for fuel cell and hybrid vehicles. The major objectives for this dc-dc converter technology are to meet: Higher efficiency (92%); High coolant temperature,e capability (105 C); High reliability (15 Years/150,000miles); Smaller volume (5L); Lower weight (6kg); and Lower cost ($75/kW). The key technical challenge for these converters is the 105 C coolant temperatures. The power switches and magnetics must be designed to sustain these operating temperatures reliably, without a large cost/mass/volume penalty.

Multi-level cascaded DC/DC converters for PV applications

Directory of Open Access Journals (Sweden)

Ahmed A.A. Hafez

2015-12-01

Full Text Available A robust multi-level cascaded DC/DC system for Photovoltaic (PV application is advised in this article. There are three PV generators, each is coupled to a half-bridge buck cell. Each PV-generator–buck-converter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal and abnormal conditions was comprehensively investigated. Internal Model Control (IMC technique was adopted for tuning the controllers. An elaborate switching modulation strategy was used to reduce the current ripple and inductor size, while maintaining high efficiency. Annotative, simple and robust remedial strategies were proposed to mitigate different anticipated faults. Comprehensive simulation results in Matlab environment were illustrated for corroborating the performance of the advised cascaded DC/DC system under normal/abnormal conditions. The proposed system enjoys the merits of independency, reduced volumetric dimensions and improved efficiency. Furthermore, the system is inherently fault-tolerant.

Valores humanos y voluntariado: Un estudio en personas mayores

Directory of Open Access Journals (Sweden)

Antonio Ariza-Montes

2017-02-01

Diseño/metodología: Tras un análisis exploratorio inicial, se plantea un modelo de regresión logística para determinar en qué medida el catálogo de valores personales que posee un individuo ayuda a explicar la actividad de voluntariado entre las personas mayores. Aportaciones y resultados: Los resultados del modelo permiten afirmar que el hecho de que una persona mayor done o no tiempo a actividades de voluntariado puede ser satisfactoriamente explicado por el conjunto de valores humanos. Los resultados obtenidos revelan que los voluntarios jubilados presentan mayor sentido de la autotrascendencia y predisposición hacia el cambio, a la vez que denotan más aversión hacia la autopromoción y la conservación. Implicaciones prácticas: Para mejorar el nivel de compromiso y la motivación de los voluntarios mayores jubilados, y afrontar con firmeza los retos que amenazan al sector no lucrativo, los responsables de los recursos humanos de las entidades del tercer sector deberán buscar la coherencia entre los valores individuales y la naturaleza de la actividad que va a desempeñar el voluntario, incrementando de este modo el grado de identificación de estas personas. Valor añadido: A pesar de la abundante literatura que relaciona el voluntariado en personas mayores con el bienestar, tanto en términos de salud como de beneficios socioemocionales, y con las motivaciones de este colectivo a la hora de ejercer el voluntariado, no es frecuente hallar investigaciones que adopten como foco de análisis el perfil de los valores personales que incitan a estos individuos a colaborar con causas altruistas.

Las personas mayores a través del cine

Directory of Open Access Journals (Sweden)

José Ramón Martínez Riera

Full Text Available Resumen: El presente artículo hace un recorrido por las diferentes etapas del envejecimiento y de la vida de las personas mayores a través del cine. El cine es un arte que transmite ideas a través de la narración de historias, mediante imágenes que impactan en el aspecto psicoemocional de las personas. El cine nos sitúa en escenarios donde se muestran las relaciones humanas, en contextos difíciles de reproducir, los cuales nos permiten explorar la esfera de los sentimientos frente a situaciones de salud-enfermedad, de ponerse en lugar del “otro”: de la persona que sueña, padece y sufre, de los profesionales que intervienen, de la familia que convive, cuida, sufre con el enfermo, de los amigos... Y entre esos escenarios, sin duda, se encuentra el proceso de envejecimiento y los diferentes factores que influyen en él. Y sin embargo no suele prestársele excesiva atención a la aportación que el cine ha realizado y realiza como elemento de reflexión, análisis, debate y aprendizaje, más allá del mero entretenimiento en el que muchas veces se enmarca el cine. Pero, ¿cómo ha tratado el cine a las personas mayores? ¿cómo aborda las interrelaciones de las personas mayores con su entorno, su familia, su proceso de salud-enfermedad, sus miedos, sus emociones? ¿Trata igual a las personas mayores con independencia de su género? Y lo que puede ser más interesante, ¿contribuye el cine a mitigar o eliminar los tópicos y estereotipos existentes en el imaginario común en torno a las personas mayores?

Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

CERN Document Server

Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Preuten, Marius; Max Rauch; Rittich, David Michael; Sammet, Jan Domenik; Wlochal, Michael

2014-01-01

A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

Auxiliary resonant DC tank converter

Science.gov (United States)

Peng, Fang Z.

2000-01-01

An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

Science.gov (United States)

Gruber, Robert P.; Gott, Robert W.

1991-01-01

In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.

Dr Stanislaw Huskowski, Mayor of Wroclaw, Poland

CERN Multimedia

Patrice Loïez

2002-01-01

Dr Stanislaw Huskowski, Mayor of Wroclaw, Poland visiting the ATLAS magnet assembly hall, building 180. From l to r: Mr Carlo Lamprecht, State Councillor, Dr Stanislaw Huskowski and Dr Peter Jenni, ATLAS Spokesperson

Development of a green mode DC/DC converter available to portable nuclear instrument

International Nuclear Information System (INIS)

Gao Feiyan; Wu Longxiong; Tan Wei; Tang Yaogeng

2010-01-01

A green mode DC/DC converter was developed which suitable to the portable nuclear instrument which is powered by battery and is sometime at stand-by mode. Some updated control approaches such as pseudo-resonant type power supply control and synchronous rectification were adopted to makethe DC/DC converter operate with low power consumption and high efficiency. The test results the battery can be prolonged with this converter. (authors)

BIENESTAR PSICOLOGICO: ADULTOS MAYORES, ACTIVOS A TRAVES DEL VOLUNTARIADO

OpenAIRE

FERRADA MUNDACA; LESLIE ISABEL; FERRADA MUNDACA; LESLIE ISABEL

2011-01-01

El propósito del presente estudio fue establecer el grado de bienestar psicológico en adultos mayores voluntarios del programa "Asesores Seniors" de Senama Región Bio Bio y no voluntarios, usuarios del CESF AM San Pedro de la comuna de San Pedro de la Paz. Corresponde a un estudio cuantitativo, de tipo descriptivo, correlacional y comparativo. La muestra estuvo constituida por 60 adultos mayores, donde 30 de ellos corresponde al grupo de voluntarios y los otros 30 al grupo...

Self-commutated high-voltage direct current transmission with DC circuit breakers. Backbone for the energy policy turnaround; Selbstgefuehrte Hochspannungs-Gleichstromuebertragung mit DC-Leistungsschalter. Rueckgrat fuer die Energiewende

Energy Technology Data Exchange (ETDEWEB)

Goerner, Raphael [ABB AG, Mannheim (Germany). Marketing und Vertrieb, Geschaeftsbereich Grid Systems

2013-06-01

The 'current war' between direct current and alternating current is extended by a new location. In the future, both technologies work together in order to provide a reliable power transmission in Germany and long-term in Europe. This is based on the self-guided high-voltage direct current transmission. In conjunction with direct current circuit breakers (DC circuit breaker) the power circuit breakers may help to make the transmission grids more flexible and to minimize losses.

De la brecha digital a la brecha psico-digital: Mayores y redes sociales

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Begoña Peral Peral

2015-07-01

Full Text Available En el presente estudio analizamos la evolución del concepto de la brecha digital para los mayores desde la perspectiva del envejecimiento activo y en el contexto de la utilización de las redes sociales como instrumento de comunicación. Consideramos que las variables socio-demográficas no tienen suficiente poder para explicar la utilización o no de las tecnologías de la comunicación (TIC por los mayores. Las variables de corte psicológico, como la edad cognitiva, la ansiedad tecnológica o el nivel de audacia complementan a las anteriores, e incluso, pueden ser más explicativas del comportamiento del mayor con relación a la utilización de redes sociales. Los resultados provenientes de una muestra de mayores, alumnos del Aula de Experiencia de una universidad, nos permiten confirmar que nuestras dudas acerca del estereotipo de los mayores respecto a la brecha digital son acertadas y que las variables psicológicas sirven, en mayor grado, para mostrar las diferencias significativas existentes entre usuarios y no usuarios de redes sociales en cuanto a la determinación del perfil de los mismos. El usuario mayor de redes sociales se siente más joven, experimenta un menor nivel de ansiedad tecnológica y es más audaz. En general, las características psicológicas ofrecen, por tanto, mayor poder discriminante que las socio-demográficas, por ello proponemos el concepto de brecha psico-digital.

A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs

DEFF Research Database (Denmark)

Wu, Weimin; Wang, Houqing; Liu, Yuan

2017-01-01

Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads...... such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac/dc...... converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis....

DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS

OpenAIRE

Belqasem Aljafari

2016-01-01

Resonant DC/DC converters are the class of converters, which have L-C resonant tank serving as a major part of the power conversion process. The fundamental concept of the resonant converter is that the circulating energy in an L-C resonant circuit is manageable by changing the operating frequency, and therefore the converter can condition the input power to the desired output voltage. The development in power conversion technology is steady demand for high power efficiency and high power den...

High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

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M. Drinovsky

2015-12-01

Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

On the modelling of linear-assisted DC-DC voltage regulators for photovoltaic solar energy systems

Science.gov (United States)

Martínez-García, Herminio; García-Vílchez, Encarna

2017-11-01

This paper shows the modelling of linear-assisted or hybrid (linear & switching) DC/DC voltage regulators. In this kind of regulators, an auxiliary linear regulator is used, which objective is to cancel the ripple at the output voltage and provide fast responses for load variations. On the other hand, a switching DC/DC converter, connected in parallel with the linear regulator, allows to supply almost the whole output current demanded by the load. The objective of this topology is to take advantage of the suitable regulation characteristics that series linear voltage regulators have, but almost achieving the high efficiency that switching DC/DC converters provide. Linear-assisted DC/DC regulators are feedback systems with potential instability. Therefore, their modelling is mandatory in order to obtain design guidelines and assure stability of the implemented power supply system.

A Feedback Passivation Design for DC Microgrid and Its DC/DC Converters

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Feifan Ji

2016-12-01

Full Text Available There are difficulties in analyzing the stability of microgrids since they are located on various network structures. However, considering that the network often consists of passive elements, the passivity theory is applied in this paper to solve the above-mentioned problem. It has been formerly shown that when the network is weakly strictly positive real (WSPR, the DC microgrid is stable if all interfaces between the microgrid and converters are made to be passive, which is called interface passivity. Then, the feedback passivation method is proposed for the controller design of various DC–DC converters to achieve the interface passivity. The interface passivity is different from the passivity of closed-loop systems on which the passivity based control (PBC concentrates. The feedback passivation design is detailed for typical buck converters and boost converters in terms of conditions that the controller parameters should satisfy. The theoretical results are verified by a hardware-in-loop real-time labotray (RTLab simulation of a DC microgrid with four generators.

Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest

Science.gov (United States)

Patterson, Richard; Hammoud, Ahmad

2010-01-01

DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.

A Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

DEFF Research Database (Denmark)

Shen, Yanfeng; Wang, Huai; Al-Durra, Ahmed

2018-01-01

This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant dc-dc converters, and meanwhile achieves high efficiency...... losses. The operation principles and characteristics of the proposed converter are firstly analyzed in this paper. Then the analytical solutions for the voltage gain, soft-switching, and rms currents are derived, which facilitates the parameters design and optimization. Finally, the proposed topology...... and analysis are verified with experimental results obtained from a 1-kW converter prototype....

Trans-pulmonary echocardiography as a guide for device closure of patent ductus arteriosus.

Science.gov (United States)

Kudo, Yoshiyuki; Suda, Kenji; Yoshimoto, Hironaga; Teramachi, Yozo; Kishimoto, Shintaro; Iemura, Motofumi; Matsuishi, Toyojiro

2015-08-01

The aim of this study was to develop trans-pulmonary echocardiography (TPE) to guide device closure of patent ductus arteriosus (DC-PDA). Aortography requires a large amount of contrast yet may give us an inadequate image to evaluate anatomy or residual shunt in patients with large PDA or dilated vessels and is precluded in patients with renal dysfunction. Practically, there is no imaging modality to monitor the entire procedure except for trans-esophageal echocardiography that requires general anesthesia. Subjects were seven patients with ages ranged from 6- to 77-years old and body weight > 15 kg. The size of the PDA ranged from 1.8 to 6.3 mm with pulmonary to systemic flow ratios from 1.2 to 2.2. During DC-PDA using Ampaltzer Duct Occluder or coil, an intra-cardiac echocardiographic (ICE) catheter was advanced into pulmonary arteries and standard views were developed to guide DC-PDA. We have developed two standard views; the main pulmonary artery view (MPA view) and the left pulmonary artery view (LPA view). The MPA view provided aortic short axis view equivalent to that seen by trans-thoracic echocardiography in children. The LPA view, obtained by the echo probe in the LPA and turned it up upside down, provided long axis view of the PDA allowing more precise anatomical evaluation. TPE allowed us to monitor the entire procedure and determine residual shunts. TPE in the MPA and LPA view can be an effective guide for DC-PDA. This report leads to new application of this imaging device. © 2015 Wiley Periodicals, Inc.

Distributed DC-UPS for energy smart buildings

Energy Technology Data Exchange (ETDEWEB)

Moreno-Munoz, A.; Pallares-Lopez, V.; Real-Calvo, R.J.; Gil-de-Castro, A. [Universidad de Cordoba, Area de Electronica, Dpto. Arquitectura de Computadores, Electronica y Tecnologia Electronica, Escuela Politecnica Superior, Campus de Rabanales, E-14071 Cordoba (Spain); De la Rosa, Juan Jose Gonzalez [Universidad de Cadiz, Area de Electronica, Dpto. ISA, TE y Electronica, Escuela Politecnica Superior Avda, Ramon Puyol, S/N, E-11202 Algeciras-Cadiz (Spain)

2011-01-15

Energy efficiency (EE) improvement is one of the most important targets to be achieved on every society as a whole and in buildings in particular. Energy Smart Building aims to accelerate the uptake of EE, healthy buildings that by integrating smart technology and solutions consume radically little resources while enhancing the quality of life. This paper addresses how uninterruptible power supply (UPS), particularly when configured in distributed DC mode, can become an Energy Efficient (EE) solution in high tech buildings, especially when integrated with complimentary Power Quality (PQ) measures. The paper is based upon PQ audits conducted at different IT-intensive modern building. Some of the mayor objectives of the PQ studies were: detecting the main involved disturbances by PQ monitoring, identifying the power disturbances root causes, characterizing the electromagnetic compatibility level of equipments and installation and providing guidelines for implementing energy-efficiency solutions. It was found that the main problems for the equipment installed were harmonics and voltage sag (dip). Finally, this paper demonstrates the impacts of generalized electronic devices on the PQ of the buildings and the implications on energy uses. (author)

Y-source impedance-network-based isolated boost DC/DC converter

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang

2014-01-01

A dc-dc converter with very high voltage gain is proposed in this paper for any medium-power application requiring a high voltage boost with galvanic isolation. The proposed converter topology can be realized using only two switches. With this topology a very high voltage boost can be achieved even...... with a relatively low duty cycle of the switches, and the gain obtainable is presently not matched by any existing impedance network based converter operated at the same duty ratio. The proposed converter has a Y-source impedance network to boost the voltage at the intermediate dc-link side and a push......-pull transformer for square-wave AC inversion and isolation. The voltage-doubler rectifier provides a constant dc voltage at the output stage. A theoretical analysis of the converter is presented, supported by simulation and experimental results. A 250 W down-scaled prototype was implemented in the laboratory...

Multilevel DC link inverter

Science.gov (United States)

Su, Gui-Jia

2003-06-10

A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.

Stability analysis of a high-step-Up DC grid-connected two-stage boost DC-DC converter

Directory of Open Access Journals (Sweden)

El Aroudi A.

2014-01-01

Full Text Available High conversion ratio switching converters are used whenever there is a need to step-up dc source voltage level to a much higher output dc voltage level such as in photovoltaic systems, telecommunications and in some medical applications. A simple solution for achieving this high conversion ratio is by cascading different stages of dc-dc boost converters. The individual converters in such a cascaded system are usually designed separately applying classical design criteria. However these criteria may not be applicable for the complete cascaded system . This paper first presents a glimpse on the bifurcation behavior that a cascade connection of two boost converters can exhibit. It is shown that the desired periodic orbit can undergo period doubling leading to subharmonic oscillations and chaotic regimes. Then, in order to simplify the analysis the second stage is considered as constant current sink and design-oriented analysis is carried out to obtain stability boundaries in the parameter space by taking into account slope interactions between the state variables in the two-different stages.

Studi Komparasi Fungsi Keanggotaan Fuzzy sebagai Kontroler Bidirectional DC-DC Converter pada Sistem Penyimpan Energi

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Eka Prasetyono

2015-09-01

Full Text Available Bidirectional DC-DC converter is needed in the energy storage system. The converter topology used in this paper was a non-isolated bidirectional DC-DC buck-boost converter. This converter worked in two ways, which the charging mode stored energy into battery when load current was less than nominal main DC current (set point and discharging mode transferred energy from battery to the load when its current exceeded set point value. Both of these modes worked automatically according to the load current. The charging and discharging currents were controlled by fuzzy logic controller which was implemented on microcontroller ARM Cortex-M4F STM32F407VG. This paper compares two types of fuzzy membership function (triangular and sigmoid in controlling bidirectional DC-DC converter. The results showed that fuzzy logic controller with triangle membership function and sigmoid as control bidirectional DC-DC converter had no significant different response, both had an average error for charging and discharging process under 4% with ripple current on the main DC bus around 0.5%. The computing time of program for fuzzy logic controller with triangular membership functions had 19.01% faster than sigmoid, and fuzzy logic computation time on a microcontroller with hardware floating point was 60% faster than software floating point.

Creatividad, creencias paranormales y deterioro cognitivo en personas mayores

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Inmaculada Méndez

2015-08-01

Full Text Available En el caso de las personas mayores, el pensamiento estético y la creatividad son formas de mantener activas la mente y la imaginación, contribuyendo a prevenir el deterioro cognitivo. Asimismo tener un sistema de creencias religiosas o incluso un sistema de creencias o experiencias paranormales ha demostrado ser beneficioso sobre la salud de los ancianos. El objetivo del estudio fue estudiar la relación entre la creatividad, el grado de deterioro cognitivo y las creencias paranormales. Se analizaron si existían diferencias atendiendo a características sociodemográficas. A un grupo de 36 personas mayores (16 varones con edades comprendidas entre los 66 y 95 años se le administró el Mini-Examen-Cognoscitivo (MEC, el Test CREA y la Escala Mejorada de Creencias Paranormales. Los resultados principales destacan que: los sujetos con mejor estado cognitivo son los más creativos; los menos creativos poseían más Creencias religiosas tradicionales e incluso mayor superstición; los ancianos con mejor estado cognitivo eran los menos supersticiosos. Es destacable que los varones eran más creativos, mientras que las mujeres destacaban en creencias religiosas tradicionales. El estudio permite reflexionar sobre la importancia de que los profesionales que trabajen con personas mayores lleven a cabo programas que favorezcan la creatividad e incluso recaben información sobre el sistema de creencias.

Usos de las herramientas digitales entre las personas mayores

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Javier Fombona Cadavieco

2012-10-01

Full Text Available Una sociedad «multiedades» supone diseñar y crear nuevos espacios de aprendizaje y comunicación, capaces de gestionar la demanda existente por parte de las personas mayores. En este artículo, se aborda la relación de las personas mayores con las tecnologías de la información y la comunicación (TIC y para ello se plantean dos objetivos: el primero va dirigido a conocer los recursos tecnológicos que utilizan y el segundo, a describir objetivamente los tipos de uso que estas personas hacen de las TIC. Para ello, se utiliza la técnica de encuesta, cuyos resultados son contrastados mediante grupos de discusión. En el estudio participaron 215 personas mayores usuarias de las TIC y siete grupos de discusión de cinco personas cada uno. Los resultados encontrados indican que los recursos que más utilizan los mayores son, los ordenadores e Internet y el uso que hacen de los mismos se ha agrupado en cuatro grandes categorías: formación, información, comunicación y entretenimiento, no encontrándose diferencias significativas en función del género o de la edad y sí se encontraron diferencias en cuanto a la disponibilidad de dichos recursos para uso particular en función del nivel de estudios.

Digitally intensive DC-DC converter for extreme space environments, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The Space Micro-Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

Zero-voltage DC/DC converter with asymmetric pulse-width modulation for DC micro-grid system

Science.gov (United States)

Lin, Bor-Ren

2018-04-01

This paper presents a zero-voltage switching DC/DC converter for DC micro-grid system applications. The proposed circuit includes three half-bridge circuit cells connected in primary-series and secondary-parallel in order to lessen the voltage rating of power switches and current rating of rectifier diodes. Thus, low voltage stress of power MOSFETs can be adopted for high-voltage input applications with high switching frequency operation. In order to achieve low switching losses and high circuit efficiency, asymmetric pulse-width modulation is used to turn on power switches at zero voltage. Flying capacitors are used between each circuit cell to automatically balance input split voltages. Therefore, the voltage stress of each power switch is limited at Vin/3. Finally, a prototype is constructed and experiments are provided to demonstrate the circuit performance.

A Fixed-Frequency Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

DEFF Research Database (Denmark)

Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede

2017-01-01

This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant DC-DC converters, and meanwhile achieves high efficiency...... and characteristics of the proposed converter are analyzed. Finally, a 1-kW converter prototype is built and the experimental results verify the theoretical analyses....

Pulse-width modulated DC-DC power converters

CERN Document Server

Kazimierczuk, Marian K

2008-01-01

This book studies switch-mode power supplies (SMPS) in great detail. This type of converter changes an unregulated DC voltage into a high-frequency pulse-width modulated (PWM) voltage controlled by varying the duty cycle, then changes the PWM AC voltage to a regulated DC voltage at a high efficiency by rectification and filtering. Used to supply electronic circuits, this converter saves energy and space in the overall system. With concept-orientated explanations, this book offers state-of-the-art SMPS technology and promotes an understanding of the principle operations of PWM converters,

Apoyo social dignificante del adulto mayor institucionalizado. medellin, 2008

OpenAIRE

Cardona Arango, Doris; Segura Cardona, Angela María; Ordoñez Molina, Jaime Eduardo; Estrada Restrepo, Alejandro; Osorio Gómez, Jorge Julián; Chavarriaga Maya, Lina Marcela

2011-01-01

Objetivo Analizar el apoyo social del adulto mayor residente en los Centros de Bienestar del Anciano de Medellín registrados en la Secretaría de Bienestar Social en el año 2008. Materiales Estudio descriptivo transversal, que abordó algunas características relacionadas con el apoyo social recibido por 276 adultos mayores institucionalizados en 39 centros de protección social, con fuente de información primaria. El análisis de la información fue univariado y bivariado. Resultados Los institu...

Digitally intensive DC-DC converter for extreme space environments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The Space Micro –Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

DEFF Research Database (Denmark)

Akhter, F.; Macpherson, D.E.; Harrison, G.P.

2015-01-01

of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation

DEFF Research Database (Denmark)

Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick

2017-01-01

This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...

Computer Simulation of Phase Shifted Series Resonant DC to DC Converter

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P. PARVATHY

2016-01-01

Full Text Available This paper deals with digital simulation of phase shifted series resonant DC to DC converter using Matlab Simulink. The Simulink models for open loop and closed loop systems are developed and they are used for simulation studies. This converter is capable of producing ripple free DC output. Switching losses and switching stresses are reduced by using soft switching. This converter has advantages like high power density and low switching losses. Theoretical predictions are well supported by the simulation results.

Power flow analysis for DC voltage droop controlled DC microgrids

DEFF Research Database (Denmark)

Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

2014-01-01

This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification is ca...

Uso de medicamentos en adultos mayores de Bogotá, Colombia

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Carlos Cano-Guitierrez

Full Text Available Objetivos. Determinar la frecuencia y tipo de medicamentos que utiliza un grupo de adultos mayores que viven en lacapital colombiana, y cuáles son potencialmente inapropiados, con base en los criterios revisados de Beers. Materiales y métodos. Los datos fueron obtenidos del estudio SABE (estudio de salud, bienestar y envejecimiento que se llevó a cabo en áreas urbanas y rurales de Bogotá en el 2012. Se utilizó la prueba U de Mann-Whitney para analizar las diferencias por sexo en los diferentes grupo de edad con relación al número de medicamentos tomados. Resultados. Un total de 1268 (63,4% de los adultos mayores fueron mujeres; entre los participantes, 1514 (75,7% tenían 5 años de educación básica o menos. El promedio de medicamentos tomados en general fue de 3,24 siendo mayor en mujeres (3,50 que en hombres (2,79. Un total de 549 sujetos (27,4% reportaron recibir cinco medicamentos o más. De los medicamentos utilizados, 443 (6,9% eran potencialmente inapropiados de acuerdo con los criterios de Beers. La prevalencia autorreportada de hipertensión fue de 56,9% y para diabetes de 17,5%. Solo 311 sujetos (15,6% no tomaban ningún medicamento. Conclusiones. El uso de medicamentos inapropiados es un problema importante que afecta a los adultos mayores en Bogotá. Estudios adicionales deberán identificar factores que aumentan el riesgo de polifarmacia y uso inapropiado de medicamentos y diseñar intervenciones para prevenir el uso inapropiado de medicamentos entre adultos mayores.

La calidad de vida del adulto mayor con Artritis Reumatoidea

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Clara Gallardo

2017-05-01

Full Text Available Objetivo determinar la atención de Enfermería y su incidencia en la calidad de vida del adulto mayor con artritis reumatoidea atendidos en el subcentro de salud de Ambatillo en el período Julio – Diciembre 2013. Métodos y materiales: Estudio no experimental de diseño descriptivo aplicando técnicas de observación y cuestionario cuya población fue de 30 adultos mayores en los que se detectó la necesidad de investigar la problemática, cuyos resultados indican que los principales problemas que presentan los pacientes son: dolor e inflamación articular, incapacidad músculo esquelética, discapacidad etc. Re- sultados: La problemática que se aborda es la calidad de vida del adulto mayor con esta patología pues muchas veces no se da una atención basada en el estado emocional, respuesta fisiológica, aspecto físico al que se enfrenta tanto el paciente como su núcleo familiar.es asì que el 69% de adultos mayores con artritis reumatoidea , la misma manera el 75% del personal de enfermería que labora en el Subcentro de salud de Ambatillo Conclusiones: Una vez evidenciada la problemática de estudio se presenta como propuesta la elaboración de una Guía de Atención de Enfermería el mismo que permitirá valorar en forma integral, priorizar las necesidades de atención y brindar cuidados específicos en el adulto mayor con artritis reumatoidea.

Bienestar psicológico subjetivo y personas mayores residentes

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Ana Concepción Flecha García

2014-12-01

Full Text Available La mejora del bienestar psicológico subjetivo y, con él, la calidad de vida de las personas mayores residentes es el propósito esencial de este trabajo. Los teóricos destacan la importancia que desempeña el bienestar subjetivo sobre la calidad de vida y su interés en la experiencia de envejecer. Concebimos la calidad de vida como un concepto multidimensional que engloba componentes objetivos y subjetivos referidos al bienestar físico y psico-social de las personas, y su evaluación incluye la percepción subjetiva que tiene el sujeto de estas dimensiones. Entendemos el bienestar psicológico subjetivo, como la valoración positiva, afectiva y cognitiva, de bienestar y satisfacción con la vida entendida como “estar y sentirse bien en el presente” y, “estar y sentirse bien con el propio recorrido vital”.El principal objetivo del estudio es conocer las necesidades de los residentes relacionadas con los componentes específicos del bienestar y satisfacción vital que la investigación revela mas asociados a las personas mayores –vínculos personales, vida activa, reminiscencia y recuerdos felices, optimismo-, y la satisfacción vital; conocer la conexión entre estas dimensiones e identificar posibles factores relacionados con las mismas, completan el fin de este trabajo.Se plantea un modelo metodológico que permite recoger el sentimiento y opinión de las personas mayores desde su propia experiencia de bienestar y satisfacción vital. El enfoque y su carácter interpretativo favorecen la comprensión e interpretación de la información tal y como es percibida por los participantes que viven y se relacionan en un determinado contexto social. Se elige para tal fin la orientación , realizando el posterior. Se recoge la información mediante una entrevista semiestructurada elaborada en base a los fines propuestos. La muestra se compone de 66 personas seleccionas en

Light weight, high power, high voltage dc/dc converter technologies

Science.gov (United States)

Kraus, Robert; Myers, Ira; Baumann, Eric

1990-01-01

Power-conditioning weight reductions by orders of magnitude will be required to enable the megawatt-power-level space systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. An interagency program has been initiated to develop an 0.1-kg/kW dc/dc converter technology base for these future space applications. Three contractors are in the first phase of a competitive program to develop a megawatt dc/dc converter. Researchers at NASA Lewis Research Center are investigating innovative converter topology control. Three different converter subsystems based on square wave, resonant, and super-resonant topologies are being designed. The components required for the converter designs cover a wide array of technologies. Two different switches, one semiconductor and the other gas, are under development. Issues related to thermal management and material reliability for inductors, transformers, and capacitors are being investigated in order to maximize power density. A brief description of each of the concepts proposed to meet the goals of this program is presented.

ALGUNOS ASPECTOS A CONSIDERAR SOBRE LA SEXUALIDAD DEL ADULTO MAYOR

Directory of Open Access Journals (Sweden)

Zoila Edith Hernández Zamora

2008-12-01

Full Text Available La presente investigación expone, a partir de una serie de entrevistas realizadas a una muestra de adultos mayores, aspectos relativos a la satisfacción general en la vida, así como las actitudes, conocimientos y prácticas de la sexualidad de un grupo de adultos mayores que asisten regularmente a una estancia diurna de la ciudad de Xalapa, Veracruz, México, misma que fue diseñada especialmente para este grupo etario. Se encontraron diferencias estadísticamente significativas entre la actitud hacia el ejercicio de la sexualidad de las personas mayores entre los hombres y las mujeres de la muestra, y entre .las personas que tienen pareja con relación a las que no tienen; así como que hay una diferencia estadísticamente significativa entre aquellas personas que tiene una o ninguna enfermedad y las que tienen dos o más enfermedades con respecto a su frecuencia de actividad sexual. Es de resaltar la escasez de conocimientos sobre aspectos básicos de la sexualidad que poseen estas personas mayores, lo que hace necesario el establecimiento de programas educativos que incluyan al personal de salud y a los mismos senectos.

Apendicitis aguda en el paciente senil: Factores asociados a una mayor morbimortalidad post operatoria

Directory of Open Access Journals (Sweden)

Víctor Eduardo Chian Chang

1996-04-01

Full Text Available Objetivo: Definir los factores asociados a una mayor morbilidad y mortalidad en pacientes seniles con apendicitis aguda. Material y métodos: Se realizó un estudio retrospectivo con 100 pacientes intervenidos en el Hospital Nacional Arzobispo Loayza, durante el período comprendido entre 1984 a 1994. Resultados: Se asociaron a una mayor frecuencia de complicaciones postoperatorias: edad mayor o igual a 70 años, tiempo de enfermedad mayor de 48 horas, presencia de apendicitis perforada con peritonitis localizada o generalizada (p<0.05. Además la presencia de apendicitis perforada se asoció significativamente a la presencia de absceso residual y/o fístula estercorácea (p=0.027 y la presencia de AA gangrenosa o perforada a mayor frecuencia de infección de herida operatoria (p<0.05. El antecedente de patología cardiovascular previa se asoció a mayor frecuencia de complicaciones cardiovasculares (p<0.05. Se asociaron a mayor mortalidad en AA, pacientes con intervención quirúrgica adicional a la apendicetomía (p=0.016 y presencia de AA perforada (p=0.027. Conclusiones: Los estadios avanzados de AA, así como la presencia de problema cardiovascular al momento del diagnóstico se asociaron con una mayor frecuencia de complicaciones post-operatorias. La presencia de peritonitis se asocia con la mortalidad. (Rev Med Hered 1996; 7: 62-67.

Análisis del bienestar de los adultos mayores en México

OpenAIRE

García Benítez, Julio César

2008-01-01

Esta tesis analiza el bienestar de los adultos mayores en México a partir de la teoría de los funcionamientos y capacidades de Amartya Sen. La investigación tiene dos objetivos principales: el primero es medir el bienestar del adulto mayor con una visión más amplia, en el sentido de incluir tanto indicadores objetivos como subjetivos; y el segundo objetivo es demostrar que este bienestar depende tanto de los recursos, como de los factores de conversión con los que cuenta el adulto mayor, los ...

Estereotipos sociales sobre la vejez en estudiantes mayores: un estudio de caso

OpenAIRE

Sanhueza, Javiera

2014-01-01

Frente al acelerado envejecimiento poblacional, se plantea el desafío de promocionar los derechos de ciudadanía de los mayores, especialmente aquellos relacionados con la participación social a través de la educación permanente. La investigación describe las imágenes sociales que las personas mayores asistentes al Aula de Mayores “Ciudad de Granada” manifiestan sobre la vejez, comparándolas según variables sociodemográficas. Se aplica el “Cuestionario de Evaluación de Estereotipos Negativos s...

Templo Mayor, Tenochtitlan - Calendar and Astronomy

Science.gov (United States)

Galindo Trejo, Jesús

The Templo Mayor of Tenochtitlan was the principal symbol of political power and religious control of the Mexicas. Its orientation was chosen according to ancestral calendrical traditions that considered the Mesoamerican calendar as a sacred concern. The solar alignments incorporated into this emblematic building symbolized moments that divided the solar year according to basic properties of the Mesoamerican calendar.

Digital peak current mode control with adaptive slope compensation for DC-DC converters

DEFF Research Database (Denmark)

Andersen, Karsten Holm; Nymand, Morten

2017-01-01

performance and stability of current mode control. The presented method adapt to DC-DC converter operating conditions by estimating the rising and falling inductor current slopes, to apply a current slope compensation value to obtain a constant quality factor. The experimental results verifies the theoretical......This paper presents an adaptive slope compensation method for peak current mode control of digital controlled DC-DC converters, which controls the quality factor of the complex conjugated poles at half the switching frequency. Using quality factor control enables optimization of the dynamic...

DC-Link Compensation Method for Slim DC Link Drives Fed by Soft Grid

DEFF Research Database (Denmark)

Mathe, Laszlo; Rosendahl Andersen, Henrik; Lazar, Radu

2010-01-01

Slim DC-link PWM (AC) drives for lowperformance applications are emerging on the market. Such drives equipped with a small DC-link capacitance exhibit instability tendencies, if installed on a soft line, giving a degraded performance. The total harmonic distortion (THD) and the partially weighted...... harmonic distortion (PWHD) of the line current are degraded, if resonance between the line impedance and the DC-link capacitance occurs. Likewise, the motor performance is affected negatively giving extra torque ripple, vibration and acoustic-noise emission. This paper proposes a novel DC-link compensation...

High-power three-port three-phase bidirectional DC-DC converter

NARCIS (Netherlands)

Tao, H.; Duarte, J.L.; Hendrix, M.A.M.

2007-01-01

This paper proposes a three-port three-phase bidirectional dc-dc converter suitable for high-power applications. The converter combines a slow primary source and a fast storage to power a common load (e.g., an inverter). Since this type of system is gaining popularity in sustainable energy

Precharge strategies for isolated modular DC-DC converters under two different start-up conditions

DEFF Research Database (Denmark)

Zhang, Yi; Wang, Huai; Li, Binbin

2017-01-01

The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value of capaci......The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value...... of capacitance in the IMDCC, proper precharge strategies before the start-up are significant for the safety and reliability of the whole system. This paper presents two closed-loop precharge control strategies to fully charge the sub-module (SM) capacitors of the IMDCC, considering two different start...

Modeling and analysis of fractional order DC-DC converter.

Science.gov (United States)

Radwan, Ahmed G; Emira, Ahmed A; AbdelAty, Amr M; Azar, Ahmad Taher

2017-07-11

Due to the non-idealities of commercial inductors, the demand for a better model that accurately describe their dynamic response is elevated. So, the fractional order models of Buck, Boost and Buck-Boost DC-DC converters are presented in this paper. The detailed analysis is made for the two most common modes of converter operation: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Closed form time domain expressions are derived for inductor currents, voltage gain, average current, conduction time and power efficiency where the effect of the fractional order inductor is found to be strongly present. For example, the peak inductor current at steady state increases with decreasing the inductor order. Advanced Design Systems (ADS) circuit simulations are used to verify the derived formulas, where the fractional order inductor is simulated using Valsa Constant Phase Element (CPE) approximation and Generalized Impedance Converter (GIC). Different simulation results are introduced with good matching to the theoretical formulas for the three DC-DC converter topologies under different fractional orders. A comprehensive comparison with the recently published literature is presented to show the advantages and disadvantages of each approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Alcaldes mayores y subdelegados frente a la siembra clandestina de tabaco: Papantla, 1765-1806 Alcaldes Mayores and Subdelegados coping with Tobacco Clandestine Sowing: Papantla, 1765-1806

Directory of Open Access Journals (Sweden)

Georgina Moreno Coello

2012-12-01

Full Text Available Este trabajo tiene como objeto explorar las estrategias que permitieron la persistencia de la siembra clandestina de tabaco en Nueva España, en particular en la región de Papantla. Analizar las relaciones entre los alcaldes mayores, subdelegados y empleados del monopolio del tabaco, enfatizando la protección informal de la que gozó el cultivo ilegal de parte de las autoridades provinciales y examinar cuál pudo ser el destino del ahorro, así como de las ganancias obtenidas del tabaco ilegal, particularmente en el financiamiento de actividades comerciales y crediticias que llevaban a cabo alcaldes mayores y subdelegados, especialmente en el repartimiento de mercancías.This paper explores the strategies that allowed for a persistent clandestine tobacco sowing in New Spain, mainly in the region of Papantla. It analyzes the relationship between alcaldes mayores, subdelegados and employees of the tobacco monopoly, emphasizing the informal protection given to illegal sowings by provincial authorities. It also examines the potential allocation of savings and profits from illegal tobacco, mainly in the financing of commercial activities undertaken by alcaldes mayores and subdelegados, particularly for the repartimiento.

Magnetically coupled high-gain Y-source isolated DC/DC converter

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede

2014-01-01

A new form of magnetically coupled DC/DC converter is proposed for medium power applications (250 W to 2 kW), requiring a high-voltage gain, short inductive charging time and galvanic isolation. The proposed converter can be realised using a unique Y-source impedance network and a two-switch push...

A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.

Science.gov (United States)

Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih

2012-01-01

This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters.

DC Rocks! Using Place-Based Learning to Introduce Washington DC's K-12 Students to the Geosciences

Science.gov (United States)

Mayberry, G. C.; Mattietti, G. K.

2017-12-01

The Washington DC area has interesting geology and a multitude of agencies that deal with the geosciences, yet K-12 public school students in DC, most of whom are minorities, have limited exposure to the geosciences. Geoscience agencies in the DC area have a unique opportunity to address this by introducing the geosciences to local students who otherwise may not have such an opportunity, by highlighting the geology in the students' "backyard," and by leveraging partnerships among DC-based geoscience-related agencies. The USGS and George Mason University are developing a project called DC Rocks, which will give DC's students an exciting introduction into the world of geoscience with place-based learning opportunities that will make geoscience relevant to their lives and their futures. Both the need in DC and the potential for lasting impact are great; the geosciences have the lowest racial diversity of all the science, technology, engineering, and math (STEM) fields, 89% of students in DC public schools are minorities, and there is no dedicated geoscience curriculum in DC. DC Rocks aims to give these students early exposure to the earth sciences, and encourage them to consider careers in the profession. DC Rocks will work with partner agencies to apply several methods that are recommended by researchers to increase the participation of minority students in the geosciences, including providing profoundly positive experiences that spark interest in the geosciences (Levine et al., 2007); increasing students' sense of belonging in the geosciences (Huntoon, et al, 2016); and place-based teaching practices that emphasize the study of local sites (Semken, 2005), such as DC's Rock Creek Park. DC Rocks will apply these methods by coordinating local geoscientists and resources to provide real-world examples of the geosciences' impact on students' lives. Through the DC Rocks website, educators will be able to request geoscience-related resources such as class presentations by

Radiated electromagnetic emissions of DC-DC converters

International Nuclear Information System (INIS)

Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M

2010-01-01

For the CMS tracker at SLHC a new powering scheme is considered to be mandatory to allow the detector to provide at least the same performance as today at the LHC. The baseline solution of CMS foresees the use of DC-DC converters to provide larger currents with smaller losses. An important component of most converters are inductors which, however, tend to radiate the switching noise generated by the converter. The emissions of different inductors have been measured and simulated, the coil design has been optimized and noise susceptibility measurements, with present CMS hardware, have been performed. This article summarizes the results.

Modeling, Analysis and Control of Different DC-DC Converter Topologies for Photo Voltaic Emulator

Directory of Open Access Journals (Sweden)

Mohammad Tauquir Iqbal

2016-05-01

Full Text Available This paper presents the modeling, analysis and control of different DC-DC converter topologies to emulate the photovoltaic (PV system. A PV emulator is basically a DC-DC converter having same electrical characteristics that of solar PV panel.  The emulator helps to achieve real characteristics of PV system in a better way in an environment where using actual PV systems can produce inconsistent results due to variation in weather conditions. The paper describes different types of DC-DC converters like buck, Resonant and Quasi Resonant Converter. The complete system is modelled in MATLAB® Simulink SimPowerSystem software package. The Simulation results obtained from the MATLAB® Simulink SimPowerSystem software package for different topologies under steady and dynamic conditions are analyzed and presented. An evaluation table is also presented at the end of the paper, presenting the effectiveness of each topology.

Prevalencia de polifarmacia en adultos mayores residentes de asilos de Hermosillo, Sonora

Directory of Open Access Journals (Sweden)

Andrés Canale Segovia

2014-12-01

Full Text Available El término polifarmacia se refiere a la utilización de múltiples fármacos por una persona, de manera constante. Debido a que los adultos mayores constituyen el grupo etario con mayor prevalencia de enfermedades crónico-degenerativas, la polifarmacia es un fenómeno común en poblaciones geriátricas. No se conoce con precisión cuál es la prevalencia en un grupo de ancianos asilados del estado de Sonora. Se realizó un estudio transversal, para estimar la prevalencia de polifarmacia en una muestra no probabilística de adultos mayores residentes de asilos de ancianos de Hermosillo, Sonora. La prevalencia de polifarmacia (definida como consumo concomitante de 4 o más fármacos fue de 36.1%, sin diferencias significativas respecto al tipo de enfermedades crónicas padecidas, así como a la edad y sexo de los ancianos asilados. Los sujetos con polifarmacia tuvieron un exceso de riesgo, superior a 10 veces, cuando la prescripción farmacológica era realizada por más de un médico, y tuvieron 5 veces más probabilidad de presentar algún efecto adverso a medicamentos respecto a los sujetos con ausencia de polifarmacia. La polifarmacia es un fenómeno que requiere mayor atención, control e investigación futura, toda vez que los adultos mayores son el grupo poblacional con mayor tendencia de crecimiento en México.

Tratamiento del adulto mayor con síndrome coronario agudo

Directory of Open Access Journals (Sweden)

Carolina Pemberthy-López

2016-11-01

Full Text Available El adulto mayor se encuentra en una etapa de la vida con cambios fisiológicos importantes que posee repercusiones directas e indirectas sobre su estado clínico, es así como el enfoque diagnóstico y terapéutico de sus patologías debe ser abordado desde una perspectiva diferente, con consideraciones especiales para este grupo poblacional. Lamentablemente, este grupo no ha sido bien representado en los diferentes estudios y por tanto, es mucho lo que desconocemos; su comportamiento y la eficacia de las distintas terapias no están bien establecidos. Teniendo de referencia el síndrome coronario agudo como principal causa de mortalidad en pacientes mayores de 65 años de edad, abordaremos esta entidad desde la evidencia que nos aportan algunos de los registros más importantes al respecto en adultos mayores.

Homopolar dc motor and trapped flux brushless dc motor using high temperature superconductor materials

Science.gov (United States)

Crapo, Alan D.; Lloyd, Jerry D.

1991-03-01

Two motors have been designed and built for use with high-temperature superconductor (HTSC) materials. They are a homopolar dc motor that uses HTSC field windings and a brushless dc motor that uses bulk HTSC materials to trap flux in steel rotor poles. The HTSC field windings of the homopolar dc motor are designed to operate at 1000 A/sq cm in a 0.010-T field. In order to maximize torque in the homopolar dc motor, an iron magnetic circuit with small air gaps gives maximum flux for minimum Ampere turns in the field. A copper field winding version of the homopolar dc motor has been tested while waiting for 575 A turn HTSC coils. The trapped flux brushless dc motor has been built and is ready to test melt textured bulk HTSC rings that are currently being prepared. The stator of the trapped flux motor will impress a magnetic field in the steel rotor poles with warm HTSC bulk rings. The rings are then cooled to 77 K to trap the flux in the rotor. The motor can then operate as a brushless dc motor.

Differential Mode EMI Filter Design for Isolated DC-DC Boost Converter

DEFF Research Database (Denmark)

Makda, Ishtiyaq Ahmed; Nymand, Morten

2014-01-01

A Differential Mode EMI filter for a low input voltage high-current isolated dc-dc boost converter is designed and presented in this paper. The primary side Differential Mode noise voltage is low due to the high transformer turn ratio, however, the input current is very high and since the EMI limit...... also does not change for such converters, it requires greatly optimized design approach for the filter including the correct sizing of the filter components. A complete analytical filter design process is carried out such a way that the Differential Mode noise voltage source in the converter...... is identified first. The DM noise model is then established and based on the harmonic analysis of the noise source voltage waveform, the complete Differential Mode EMI filter, including the filter resonance damping branch, is designed for a 3kW isolated dc-dc boost converter. The noise model and its theoretical...

Current Mode Control for LLC Series Resonant DC-to-DC Converters

Directory of Open Access Journals (Sweden)

Jinhaeng Jang

2015-06-01

Full Text Available Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a new current mode control scheme which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant DC-to-DC converter.

Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

Science.gov (United States)

Lee, F. C.; Mahmoud, M. F.; Yu, Y.

1980-04-01

The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

Science.gov (United States)

Lee, F. C.; Mahmoud, M. F.; Yu, Y.

1980-01-01

The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

Design of PI Controlled Non Isolated Bidirectional DC to DC Converter for Electric Vehicle Application

Science.gov (United States)

Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.

2018-04-01

Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.

Nivel de autotrascendencia en un grupo de adultos mayores mexicanos

OpenAIRE

Raúl Fernando Guerrero Castañeda; Ricardo Lara Pérez

2017-01-01

Introducción: La autotrascendencia es una expansión multidimensional personal, una conexión con los demás, el entorno y/o una entidad superior, está relacionada con el bienestar personal del adulto mayor. Objetivo: Determinar el nivel de autotrascendencia de un grupo de adultos mayores mexicanos. Materiales y Métodos: Estudio descriptivo de corte transversal; realizado en tres centros gerontológicos de Celaya, Guanajuato, México, muestra probabilística aleatoria n=118. Se incluyeron adultos m...

NIVEL DE AUTOTRASCENDENCIA EN UN GRUPO DE ADULTOS MAYORES MEXICANOS

OpenAIRE

Guerrero Castañeda, Raúl Fernando; Lara Pérez, Ricardo

2017-01-01

RESUMEN Introducción: La autotrascendencia es una expansión multidimensional personal, una conexión con los demás, el entorno y/o una entidad superior, está relacionada con el bienestar personal del adulto mayor. Objetivo: Determinar el nivel de autotrascendencia de un grupo de adultos mayores mexicanos. Materiales y Métodos: Estudio descriptivo de corte transversal; realizado en tres centros gerontológicos de Celaya, Guanajuato, México, muestra probabilística aleatoria n=118. Se incluyero...

Application of Distributed DC/DC Electronics in Photovoltaic Systems

Science.gov (United States)

Kabala, Michael

In a typical residential, commercial or utility grade photovoltaic (PV) system, PV modules are connected in series and in parallel to form an array that is connected to a standard DC/AC inverter, which is then connected directly to the grid. This type of standard installation; however, does very little to maximize the energy output of the solar array if certain conditions exist. These conditions could include age, temperature, irradiance and other factors that can cause mismatch between PV modules in an array that severely cripple the output power of the system. Since PV modules are typically connected in series to form a string, the output of the entire string is limited by the efficiency of the weakest module. With PV module efficiencies already relatively low, it is critical to extract the maximum power out of each module in order to make solar energy an economically viable competitor to oil and gas. Module level DC/DC electronics with maximum power point (MPP) tracking solves this issue by decoupling each module from the string in order for the module to operate independently of the geometry and complexity of the surrounding system. This allows each PV module to work at its maximum power point by transferring the maximum power the module is able to deliver directly to the load by either boosting (stepping up) the voltage or bucking (stepping down) the voltage. The goal of this thesis is to discuss the development of a per-module DC/DC converter in order to maximize the energy output of a PV module and reduce the overall cost of the system by increasing the energy harvest.

Quasiperiodicity and Torus Breakdown in a Power Electronic DC/DC Converter

DEFF Research Database (Denmark)

Zhusubaliyev, Zhanybai; Soukhoterin, Evgeniy; Mosekilde, Erik

2007-01-01

This paper discusses the mechanisms of torus formation and torus destruction in a dc/dc converter with relay control and hysteresis. We establish a chart of the dynamical modes in the input voltage versus load resistance parameter plane. This chart displays several different torus bifurcations...

Biosignal-guided personalized therapy

Directory of Open Access Journals (Sweden)

von Stülpnagel Lukas

2017-09-01

Full Text Available Sudden cardiac death (SCD is the leading single cause of death in the industrialized world. Current guidelines recommend a prophylactic implantation of an implantable cardioverter-defibrillator (ICD in patients with reduced left-ventricular ejection fraction (LVEF ≤ 35%. However, most deaths after myocardial infarction (MI occur in patients with normal or moderately reduced LVEF (>35%. There is a large body of evidence that cardiac autonomic dysfunction after MI is linked to increased susceptibility to malignant arrhythmias. Deceleration capacity of heart rate (DC and periodic repolarization dynamics (PRD are novel ECG-based risk markers, which capture different facets of cardiac autonomic dysfunction. Both parameters are strong and independent predictors of mortality and SCD after MI. Previous studies indicated that combined assessment of DC and PRD allows identification of a new high-risk group among post-infarction patients that is not addressed by current guidelines, thus opening new perspectives for biosignal-guided personalized therapies.

DC Distribution Systems and Microgrids

DEFF Research Database (Denmark)

Dragicevic, Tomislav; Anvari-Moghaddam, Amjad; Quintero, Juan Carlos Vasquez

2017-01-01

summarized. Due to its attractive characteristics in terms of compliance with modern generation, storage and electronic load technologies, high reliability and current carrying capacity, as well as simple control, DC systems are already an indispensable part of power systems. Moreover, the existing......A qualitative overview of different hardware topologies and control systems for DC MGs has been presented in this chapter. Some challenges and design considerations of DC protections systems have also been discussed. Finally, applications of DC MGs in emerging smart grid applications have been...... challenges such as protection issues will be effectively resolved in the near future due to fast progress of semiconductor technology which is a key enabler cheap and reliable future DC solid-state protection systems. Therefore, it is the view of the author that more and more DC systems will appear...

Analysis of the Coupling Behavior of PEM Fuel Cells and DC-DC Converters

Directory of Open Access Journals (Sweden)

Achim Kienle

2009-03-01

Full Text Available The connection between PEM fuel cells and common DC-DC converters is examined. The analysis is model-based and done for boost, buck and buck-boost converters. In a first step, the effect of the converter ripples upon the PEM fuel cell is shown. They introduce oscillations in the fuel cell. Their appearance is explained, discussed and possibilities for their suppression are given. After that, the overall behaviors of the coupled fuel cell-converter systems are analyzed. It is shown, that neither stationary multiplicities nor oscillations can be introduced by the couplings and therefore separate control approaches for both the PEMFC and the DC-DC converters are applicable.

Single Event Burnout in DC-DC Converters for the LHC Experiments

Energy Technology Data Exchange (ETDEWEB)

Claudio H. Rivetta et al.

2001-09-24

High voltage transistors in DC-DC converters are prone to catastrophic Single Event Burnout in the LHC radiation environment. This paper presents a systematic methodology to analyze single event effects sensitivity in converters and proposes solutions based on de-rating input voltage and output current or voltage.

Area-Efficiency Trade-Offs in Integrated Switched-Capacitor DC-DC Converters

DEFF Research Database (Denmark)

Spliid, Frederik Monrad; Larsen, Dennis Øland; Knott, Arnold

2016-01-01

This paper analyzes the relationship between efficiency and chip area in a fully integrated switched capacitor voltage divider dc-dc converter implemented in 180nm-technology and a 1/2 topology. A numerical algorithm for choosing the optimal sizes of individual components, in terms of power loss...

Egr2 induced during DC development acts as an intrinsic negative regulator of DC immunogenicity.

Science.gov (United States)

Miah, Mohammad Alam; Byeon, Se Eun; Ahmed, Md Selim; Yoon, Cheol-Hee; Ha, Sang-Jun; Bae, Yong-Soo

2013-09-01

Early growth response gene 2 (Egr2), which encodes a zinc finger transcription factor, is rapidly and transiently induced in various cell types independently of de novo protein synthesis. Although a role for Egr2 is well established in T-cell development, Egr2 expression and its biological function in dendritic cells (DCs) have not yet been described. Here, we demonstrate Egr2 expression during DC development, and its role in DC-mediated immune responses. Egr2 is expressed in the later stage of DC development from BM precursor cells. Even at steady state, Egr2 is highly expressed in mouse splenic DCs. Egr2-knockdown (Egr2-KD) DCs showed increased levels of major histocompatability complex (MHC) class I and II and co-stimulatory molecules, and enhanced antigen uptake and migratory capacities. Furthermore, Egr2-KD abolished SOCS1 expression and signal transducer and activator of transcription 5 (STAT5) activation during DC development, probably resulting in the enhancement of IL-12 expression and Th1 immunogenicity of a DC vaccine. DC-mediated cytotoxic T lymphocyte (CTL) activation and antitumor immunity were significantly enhanced by Egr2-KD, and impaired by Egr2 overexpression in antigen-pulsed DC vaccines. These data suggest that Egr2 acts as an intrinsic negative regulator of DC immunogenicity and can be an attractive molecular target for DC vaccine development. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of DC link control strategies on the power-flow convergence of integrated AC–DC systems

Directory of Open Access Journals (Sweden)

Shagufta Khan

2016-03-01

Full Text Available For the power-flow solution of integrated AC–DC systems, five quantities are required to be solved per converter, against three independent equations available. These three equations consist of two basic converter equations and one DC network equation, corresponding to each converter. Thus, for solution, two additional equations are required. These two equations are derived from the control specifications adopted for the DC link. Depending on the application, several combinations of valid control specifications are possible. A set of valid control specifications constitutes a control strategy. It is observed that the control strategy adopted for the DC link strongly affects the power-flow convergence of integrated AC–DC systems. This paper investigates how different control strategies affect the power flow convergence of integrated AC–DC systems. Sequential method is used to solve the DC variables in the Newton Raphson (NR power flow model. Seven typical control strategies have been taken into consideration. This is validated by numerous case studies carried out with multiple DC links incorporated in the IEEE 118-bus and 300-bus test systems.

Desarrollo de un Taller de risaterapia con un grupo de personas mayores

Directory of Open Access Journals (Sweden)

Pablo Santos M.

2018-01-01

Full Text Available Introducción: Las personas mayores constituyen un grupo de edad que requiere especial atención. En este contexto, se hace necesario implementar actividades que fomenten el envejecimiento activo y su bienestar psicosocial. Objetivo: se investigan los beneficios de la participación en un taller de risaterapia sobre el bienestar subjetivo y psicológico de un grupo de personas mayores a partir de su experiencia. Metodología: Estudio con enfoque cualitativo mediante entrevistas semiestructuradas a 57 personas mayores no institucionalizadas, con edades comprendidas entre los 60 y 88 años, socias de tres Centros de Día para personas mayores de la Gerencia Territorial de Servicios Sociales de Salamanca (Junta de Castilla y León. El taller de risaterapia se desarrolló durante cuatro sesiones de tres horas de duración cada una, con una periodicidad semanal. Resultados: El análisis de contenido de los discursos de los participantes develan categorías vinculadas a crecimiento personal, mejora del estado de ánimo, valoración de la risa como actividad física y lúdica, incremento de la motivación y fortalecimiento de las relaciones interpersonales. Conclusiones: Los resultados muestran los efectos positivos de los talleres de risaterapia sobre el bienestar psicológico y subjetivo de las personas mayores.

Investigation of DC-DC Boost Converter for Reliability of Operational Planning

DEFF Research Database (Denmark)

Khazraj, Hesam; Ashouri, Mani; Silva, Filipe Miguel Faria da

2018-01-01

of the interests related to reliability is the power semiconductor switches, which are the most vulnerable elements. The failure of one-power switches can reduce the system reliability. Interleaved technique for DC-DC converters is a redundant strategy to improve the reliability, but at the cost of increasing...

Comparison of solar panel cooling system by using dc brushless fan and dc water

International Nuclear Information System (INIS)

Irwan, Y M; Leow, W Z; Irwanto, M; M, Fareq; Hassan, S I S; Amelia, A R; Safwati, I

2015-01-01

The purpose of this article is to discuss comparison of solar panel cooling system by using DC brushless fan and DC water pump. Solar photovoltaic (PV) power generation is an interesting technique to reduce non-renewable energy consumption and as a renewable energy. The temperature of PV modules increases when it absorbs solar radiation, causing a decrease in efficiency. A solar cooling system is design, construct and experimentally researched within this work. To make an effort to cool the PV module, Direct Current (DC) brushless fan and DC water pump with inlet/outlet manifold are designed for constant air movement and water flow circulation at the back side and front side of PV module representatively. Temperature sensors were installed on the PV module to detect temperature of PV. PIC microcontroller was used to control the DC brushless fan and water pump for switch ON or OFF depend on the temperature of PV module automatically. The performance with and without cooling system are shown in this experiment. The PV module with DC water pump cooling system increase 3.52%, 36.27%, 38.98%in term of output voltage, output current, output power respectively. It decrease 6.36 °C compare than to PV module without DC water pump cooling system. While DC brushless fan cooling system increase 3.47%, 29.55%, 32.23%in term of output voltage, output current, and output power respectively. It decrease 6.1 °C compare than to PV module without DC brushless fan cooling system. The efficiency of PV module with cooling system was increasing compared to PV module without cooling system; this is because the ambient temperature dropped significantly. The higher efficiency of PV cell, the payback period of the system can be shorted and the lifespan of PV module can also be longer. (paper)

Factores que inciden en la soledad residencial de las personas mayores que viven solas

Directory of Open Access Journals (Sweden)

Julia Gallo Estrada

2015-03-01

Full Text Available El aumento de la esperanza de vida, los cambios sociales y los cambios en la estructura familiar hacen que cada vez sean más y durante más tiempo las personas mayores que prefieren vivir solas, incluso cuando necesitan cuidados. Este trabajo tiene como objetivo describir el problema de la soledad residencial de las personas mayores profundizando en los factores que pueden influir en esta circunstancia. Se ha realizado una estrategia de búsqueda bibliográfica a partir de los conceptos nucleares: "personas mayores de 75 años que viven solas", "persona mayor frágil", "soporte social y entorno", "nivel de instrucción" y "familia". La información recopilada de las aportaciones científicas realizadas en este campo pone de manifiesto la necesidad de considerar prioritario conocer la opinión de las personas mayores y sus familias sobre los factores que modifican la permanencia en el domicilio.

75 FR 47199 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-10 Series Airplanes, DC-9-30...

Science.gov (United States)

2010-08-05

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-10 Series Airplanes, DC-9-30 Series... existing airworthiness directive (AD), which applies to all McDonnell Douglas Model DC-9-10 series..., 2010). That AD applies to all McDonnell Douglas Corporation Model DC-9-10 series airplanes, DC-9-30...

A Novel Single Switch Transformerless Quadratic DC/DC Buck-Boost Converter

DEFF Research Database (Denmark)

Mostaan, Ali; A. Gorji, Saman; N. Soltani, Mohsen

2017-01-01

A novel quadratic buck-boost DC/DC converter is presented in this study. The proposed converter utilizes only one active switch and can step-up/down the input voltage, while the existing single switch quadratic buck/boost converters can only work in step-up or step-down mode. First, the proposed ...

PACIENTE ADULTO MAYOR Y CIRUGÍA NO CARDÍACA: ¿QUÉ DEBEMOS SABER?

OpenAIRE

Nazar J,Claudio; Zamora H,Maximiliano; Fuentes H,Ricardo; Lema F,Guillermo

2015-01-01

Los procedimientos quirúrgicos en pacientes adultos mayores son cada vez más frecuentes. Se caracterizan por tener mayor morbimortalidad que los realizados en pacientes más jóvenes, por lo que es esencial una apropiada evaluación preoperatoria, una acuciosa monitorización intraoperatoria y un adecuado manejo del período postoperatorio. La edad conlleva una serie de cambios fisiológicos y una mayor incidencia de enfermedades crónicas, que en conjunto determinan una disminución de las reservas ...

Drilling history core hole DC-8

International Nuclear Information System (INIS)

1978-10-01

Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored

Drilling history core hole DC-8

Energy Technology Data Exchange (ETDEWEB)

1978-10-01

Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored.

Characterization of diode valve in medium voltage dc/dc converter for wind turbines

DEFF Research Database (Denmark)

Dincan, Catalin Gabriel; Kjær, Philip Carne

2016-01-01

This paper proposes a methodology for characterization of medium voltage (MV), medium frequency (MF) rectifier diode valve. The intended application is for 10MW dc/dc converters used in DC offshore wind turbines. Sensitivity to semiconductor component parameter variation, snubber component tolera...... tolerance, influence of temperature and stray capacitance are analyzed. It is concluded that the largest impact on sensitivity is given by reverse recovery charge variation and differences of temperature between adjacent devices....

Operation and control of a DC-grid offshore wind farm under DC transmission system faults

DEFF Research Database (Denmark)

Deng, Fujin; Chen, Zhe

2013-01-01

. Consequently, the protection and control strategies of dc systems need to be established. This paper studies a dc-grid offshore wind farm, where the wind power collection system and power transmission system adopt dc technology. In this paper, the redundancy of the HVDC transmission system under faults...... is studied, and a fault ridethrough strategy for the dc-grid offshore wind farm is proposed. The proposed strategy can effectively minimize the impacts of the power transmission system disturbance on the offshore wind farm, and on the ac grid. A dc-grid offshore wind farm example is simulated with PSCAD....../EMTDC, and the results validate the feasibility of the presented redundancy configuration and operation approach, and the fault ridethrough control strategy....

Open- and Short-Circuit Fault Identification for a Boost dc/dc Converter in PV MPPT Systems

Directory of Open Access Journals (Sweden)

Diego R. Espinoza Trejo

2018-03-01

Full Text Available This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT in Photovoltaic (PV systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD controller is suggested for PV voltage regulation at the maximum power point (MPP. In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.

Research on Two-channel Interleaved Two-stage Paralleled Buck DC-DC Converter for Plasma Cutting Power Supply

DEFF Research Database (Denmark)

Yang, Xi-jun; Qu, Hao; Yao, Chen

2014-01-01

As for high power plasma power supply, due to high efficiency and flexibility, multi-channel interleaved multi-stage paralleled Buck DC-DC Converter becomes the first choice. In the paper, two-channel interleaved two- stage paralleled Buck DC-DC Converter powered by three-phase AC power supply...

Black Perceptions of the Mayor: An Empirical Test.

Science.gov (United States)

Foster, Lorn S.

1978-01-01

During the past ten years Blacks have increased their participation in the urban political process. In a few urban areas, such as Newark and Detroit, Blacks constitute an electoral majority and have elected Black mayors. (Author/RLV)

Pulsed-DC selfsputtering of copper

International Nuclear Information System (INIS)

Wiatrowski, A; Posadowski, W M; Radzimski, Z J

2008-01-01

At standard magnetron sputtering conditions (argon pressure ∼0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (∼550W/cm 2 ). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%

Pulsed-DC selfsputtering of copper

Science.gov (United States)

Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

2008-03-01

At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.

DC injection into low voltage AC networks

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

Eficacia de la coronariografía en el adulto mayor

Directory of Open Access Journals (Sweden)

Luis Enrique Arozarena Díaz

2015-06-01

Full Text Available Introducción: se considera adulto mayor a toda persona cuya edad supere los 60 años, aunque se admite que este criterio no toma en cuenta: los procesos degenerativos, las alteraciones clínicas crónicas, la incapacidad y la dependencia. Objetivo: determinar la eficacia y seguridad de la coronariografía y el intervencionismo coronario percutáneo en el adulto mayor. Material y método: se realizó un estudio retrospectivo y descriptivo con los 5715 pacientes. A estos se les realizó una coronariografía en el laboratorio de hemodinámica del Cardiocentro procedente de Pinar del Río, entre 2010 y 2013. La muestra quedó formada por los 1933 mayores de 60 años. La información se obtuvo de la base de datos ANGYCOR, considerando las características clínico-angiográficas. Resultados: el diagnóstico más frecuente resultó la angina estable (43,5%. La edad promedio de 60 a 70 años, predominando el grupo de 60 a 69 años; la masculinidad (77,2% y la hipertensión arterial (64,9%. El 7,8% de los enfermos tenían una revascularización anterior. En el 98,0% el proceder resultó exitoso. Se concluyó que el índice de complicaciones y la mortalidad en coronariografía del adulto mayor es bajo, con elevado porcentaje de éxito, por lo que parece proceder eficaz y seguro. Conclusiones: el índice de realización de coronariografía a pacientes mayores de 60 años es bajo. La indicación del estudio, la presencia de enfermedad multivasos y del tronco de coronaria izquierda disminuyen a medida que aumenta la edad. La frecuencia de complicaciones, la mortalidad es nula con elevado índice de éxito.

Transition towards DC micro grids: From an AC to a hybrid AC and DC energy infrastructure

Directory of Open Access Journals (Sweden)

Evi Ploumpidou

2017-12-01

Full Text Available Our electricity is predominantly powered by alternating current (AC, ever since the War of Currents ended in the favor of Nicola Tesla at the end of the 19th century. However, lots of the appliances we use, such as electronics and lights with light-emitting diode (LED technology, work internally on direct current (DC and it is projected that the number of these appliances will increase in the near future. Another contributor to the increase in DC consumption is the ongoing electrification of mobility (Electric Vehicles (EVs. At the same time, photovoltaics (PV generate DC voltages, while the most common storage technologies also use DC. In order to integrate all these appliances and technologies to the existing AC grid, there is a need for converters which introduce power losses. By distributing DC power to DC devices instead of converting it to AC first, it is possible to avoid substantial energy losses that occur every time electricity is converted. This situation initiated the concept for the implementation of the DC-Flexhouse project. A prototype DC installation will be developed and tested in one of the buildings of the developing living lab area called the District of Tomorrow (De Wijk van Morgen which is located in Heerlen, the Netherlands. A neighborhood cooperative (Vrieheide cooperatie is also part of the consortium in order to address the aspect of social acceptance. Although DC seems to be a promising solution for a more sustainable energy system, the business case is still debatable due to both technology- and market-related challenges. The current energy infrastructure is predominantly based on AC, manufacturers produce devices based on AC standards and people are using many AC products across a long life span. This Smart Energy Buildings & Cities (SEB&C PDEng project is a contribution to the DC-Flexhouse project. The aim is to analyze the challenges in the transition to DC micro grids, assess the market potential of DC

DC-Compensated Current Transformer.

Science.gov (United States)

Ripka, Pavel; Draxler, Karel; Styblíková, Renata

2016-01-20

Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.

High voltage dc cables

Energy Technology Data Exchange (ETDEWEB)

Bjustrom, B

1965-12-01

How stress distribution in dc cables varies with temperature and stress level, influence of polarity reversals and space charges, and different types of overvoltage to which dc cable may be subjected are discussed. Design problems, especially as related to corrosion protection and to mechanical stress caused by wire armoring during manufacturing and laying, accessories and work done on test methods, and the possibility of designing 400 to 600 kV dc cables for transmitting 2000 to 4000 MW are described.

Comparative evaluation of bidirectional dual active bridge DC-DC converter variants

NARCIS (Netherlands)

Sfakianakis, G.; Everts, J.; Huisman, H.; Lomonova, E.A.

2016-01-01

For the realization of DC-DC converters in automotive industry, the Dual Active Bridge (DAB) converter seems to be a promising choice because of its soft-switching and high-power-density capability. Contrary to the traditional 3 level - 3 level (3-3L) DAB, a 3 level - 5 level (3-5L) DAB can operate

RELACIÓN MÉDICO PACIENTE: DERECHOS DEL ADULTO MAYOR

Science.gov (United States)

Barrantes-Monge, Melba; Rodríguez, Eduardo; Lama, Alexis

2009-01-01

Existen prejuicios en relación con la vejez, incluso entre los profesionales que se dedican a la gerontología. Uno común y peligroso es considerar que los viejos son todos enfermos o discapacitados. La relación médico-paciente es la piedra angular de la práctica y ética médicas. Para alcanzar el respeto por los adultos mayores es necesaria una medicina prudente, basada en una práctica en la cual la reflexión ética y clínica pueda contribuir. Esto último es posible si se hacen valer los derechos del adulto mayor, en particular como paciente para la toma de decisiones. PMID:20379380

Improvement of burst-mode control of piezoelectric transformer based DC/DC converter

International Nuclear Information System (INIS)

Vasic, Dejan; Liu, Yuan-Ping; Costa, François; Schwander, Denis; Wu, Wen-Jong

2013-01-01

Burst-mode operation is adopted sometimes in piezoelectric transformer based converters for two major purposes: (1) to achieve voltage regulation in DC/DC converters and (2) to achieve dimming control in backlight inverters. Burst-mode control enables the converter to operate at a constant switching frequency as well as to maintain good efficiency at light load conditions. However, in practice, the piezoelectric transformer cannot instantly stop vibrating in the burst-mode due to its high quality factor. The delay in the output voltage change resulting from this behavior influences the accuracy of the regulation. This paper proposes a control strategy to make the piezoelectric transformer stop more quickly so as to enhance the accuracy of burst-mode control. The proposed method only modifies the control signal of the burst-mode driving circuit. The proposed control strategy is verified by experiments in a step-down 9 W DC/DC converter. (paper)

Los derechos de las personas mayores

Directory of Open Access Journals (Sweden)

Francisco Javier Leturia Arrazola

2011-12-01

Full Text Available Este trabajo pretende reflejar el modelo y metodología de inclusión de la perspectiva de los derechos en el modelo de intervención psicosocial orientado a la calidad de vida (Shalock y Verdugo 2006 de las personas mayores, aplicado por los autores y sus equipos en los últimos años, especialmente en Matia Fundazioa, y su utilidad como estrategia preferente de prevención del trato inadecuado. Ha sido becado y publicado por el Defensor del Pueblo del País Vasco, “Ararteko” (2008 en el libro: “Los derechos de las personas mayores y la prevención del mal trato” This work tries to reflect the model and methodology for mainstreaming of rights in the psychosocial intervention model aimed at the quality of life (Shalock and Verdugo, 2006 of the elderly operated by the authors and their teams in recent years Matia Foundation and especially its usefulness as a preferred strategy for the prevention of improper treatment. It was granted and published by the Basque Country Ombudsman “Ararteko” (2008 on the book: “The rights of the elderly and prevention of ill treatment”Download this paper from SSRN: http://ssrn.com/abstract=1963683

Modular Power System Configured with Standard Product Hybrid DC-DC Converters, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — VPT proposes an innovative concept whereby complex NASA space power electronic systems can be configured using a small number of qualified hybrid DC-DC converter and...

DIAGNOSTIC/PROGNOSTIC EXPERIMENTS FOR CAPACITOR DEGRADATION AND HEALTH MONITORING IN DC-DC CONVERTERS

Data.gov (United States)

National Aeronautics and Space Administration — Studying and analyzing the ageing mechanisms of electronic components avionics in systems such as the GPS and INAV are of critical importance. In DC-DC power...

Simulating and Testing a DC-DC Half-Bridge SLR Converter

Science.gov (United States)

2013-06-01

future pulse power demands with ship power, a large bank of capacitors or similar rapid discharge source is required. If capacitors are charged...Single Pulsed Avalanche Energy (j) I" Avalanche Current (i) E,, Repetilive Avalanche Energy (i) dv/dt Peak Diode Recovery dv/dt ® Po Total Power...SLR), battery charging, DC-DC, pulse power, power electronics, SLR converter 15. NUMBER OF PAGES 119 16. PRICE CODE 17. SECURITY CLASSIFICATION

Efficient Visible Light Communication Transmitters Based on Switching-Mode dc-dc Converters

Science.gov (United States)

2018-01-01

Visible light communication (VLC) based on solid-state lighting (SSL) is a promising option either to supplement or to substitute existing radio frequency (RF) wireless communication in indoor environments. VLC systems take advantage of the fast modulation of the visible light that light emitting diodes (LEDs) enable. The switching-mode dc-to-dc converter (SMCdc-dc) must be the cornerstone of the LED driver of VLC transmitters in order to incorporate the communication functionality into LED lighting, keeping high power efficiency. However, the new requirements related to the communication, especially the high bandwidth that the LED driver must achieve, converts the design of the SMCdc-dc into a very challenging task. In this work, three different methods for achieving such a high bandwidth with an SMCdc-dc are presented: increasing the order of the SMCdc-dc output filter, increasing the number of voltage inputs, and increasing the number of phases. These three strategies are combinable and the optimum design depends on the particular VLC application, which determines the requirements of the VLC transmitter. As an example, an experimental VLC transmitter based on a two-phase buck converter with a fourth-order output filter will demonstrate that a bandwidth of several hundred kilohertz (kHz) can be achieved with output power levels close to 10 W and power efficiencies between 85% and 90%. In conclusion, the design strategy presented allows us to incorporate VLC into SSL, achieving high bit rates without damaging the power efficiency of LED lighting. PMID:29642455

Well coupled, low noise, dc SQUIDS

International Nuclear Information System (INIS)

Muhlfelder, B.; Beall, J.A.; Cromar, M.W.; Johnson, W.W.; Ono, R.H.

1985-01-01

The authors have designed, fabricated, and tested a Double Transformer (DT) coupled dc SQUID (Superconducting Quantum Interference Device) with low noise, an input inductance of 1μH and a smooth input-output characteristic. A transmission line model is presented to explain a resonance in the input-output characteristic of early versions of this device. Guided by the results of numerical simulations a new version of this device has been built and tested. Experimental results are presented that show that the resonance can be moved to a higher voltage by reducing the area of the SQUID loop. The voltage-external flux characteristic of some of these new devices agrees to within 10% with computer simulations. The minimum detectable energy per unit bandwidth (MDE) referred to the SQUID loop, is 10h, where h is Planck's constant. Computer simulations indicate an MDE of 6h

DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

DEFF Research Database (Denmark)

Liu, Changjin; Xu, Dehong; Zhu, Nan

2013-01-01

Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

Perfil de los adultos mayores usuarios de atención primaria

Directory of Open Access Journals (Sweden)

Fabianne de Jesus Dias de Sousa

2017-05-01

Full Text Available Introducción: Las proyecciones indican que Brasil será el sexto país del mundo con el mayor número de adultos mayores. El objetivo de este estudio fue caracterizar las condiciones de perfil y de vida socio-demográficos y de salud de los usuarios adultos mayores de la atención primaria de un municipio en la región amazónica del Brasil. Es oportuno porque el envejecimiento de la población está creciendo rápidamente, especialmente en países en desarrollo como el Brasil. Materiales y Métodos: Estudio transversal con una muestra de 441 individuos con edad inferior a 60 años de la población de usuarios de la atención básica en el municipio de Benevides, en la Amazonia brasileña. Os datos fueron obtenidos a través del Elder notebook, un protocolo clínico del Ministerio de la Salud. La prueba del chi-cuadrado con un nivel de significancia de 5% para explorar fue utilizada las asociaciones entre las variables de las condiciones de salud y de vida, y las variables socio-demográficas. Resultados: Se presentaron un perfil predominantemente joven adultos mayores (46.0%, que no practican actividad física (p<0.02, con condiciones crónicas y uso de drogas para inducir el sueño (p<0.05. Discusión y Conclusiones: El perfil de vida desfavorable y de salud encontrados en adultos mayores exige la adopción de medidas reforzadas, sobre la salud y los presupuestos de atención integral como un desafío para efectuar la colocación de sus necesidades, principalmente por la enfermería, en la Atención Básica de Salud en áreas más necesitadas de la región amazónica. Cómo citar este artículo: Sousa FJD, Andrade FS. Perfil de los adultos mayores usuarios de atención primaria. Rev Cuid. 2017; 8(2: 1573-81. http://dx.doi.org/10.15649/cuidarte.v8i2.376

Sobrecarga y calidad de vida del cuidador principal del adulto mayor

Directory of Open Access Journals (Sweden)

Jack Roberto Silva Fhon

2016-09-01

Full Text Available Objetivo: Determinar la sobrecarga de trabajo y la calidad de vida del cuidador principal del adulto mayor atendido en un consultorio de geriatría. Metodología: Estudio cuantitativo, descriptivo, de corte transversal, realizado con 183 adultos mayores y sus respectivos cuidadores atendidos en un consultorio de geriatría. Para la recolección de los datos, fueron utilizados los instrumentos de perfil demográfico para el adulto mayor y su cuidador Escala de Zarit y The Medical Outcomes Study 36-item (sf-36. El análisis se realizó por medio de la estadística descriptiva y de la prueba de correlación de Spearman, con un nivel de significancia de p ≤ 0,05. Resultados: En los adultos mayores, hubo predominio del sexo masculino; la edad promedio fue de 74,8 años y estaban casados/as. En los cuidadores, predominó el sexo femenino; la edad promedio fue de 44,3 años. El total de cuidadores tenían estudios superiores, estaban casados/as y eran hijos/as de los adultos mayores. Según la evaluación con la Escala de Zarit, el 18,1% presentó algún tipo de sobrecarga; en cuanto a la calidad de vida, las dimensiones con menor puntuación fueron Salud general, Salud mental y Vitalidad. Se obtuvo una correlación inversa entre la puntuación total de la Escala de Zarit y todas las dimensiones de la calidad de vida. Conclusión: Se observó que el desgaste de la calidad de vida se debe a la sobrecarga en el cuidado del adulto mayor. Por lo tanto, se hace necesario acompañar el estado de salud de los cuidadores con la finalidad de prevenir alteraciones físicas y mentales.

El liderazgo del adulto mayor en la transformación de la subcultura de un grupo de adultos mayores del Centro Diurno para el Adulto Mayor de Belén por medio de la actividad física

OpenAIRE

Murillo Campos, Edgar

2011-01-01

Tesis texto completo Se analiza el impacto que tiene la participación de líderes adultos mayores en la modificación de la subcultura del Centro Diurno para el Adulto Mayor de Belén en relación con los estilos de vida saludable por medio de la actividad física. Participaron en el estudio 7 hombres entre los 65 y 91 años de edad y 29 mujeres entre los 65 y los 100 años de edad. Entre los instrumentos están: una entrevista en el campo del liderazgo aplicada a los dirigentes del Centro Diurno ...

AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

Directory of Open Access Journals (Sweden)

Rui Li

2016-12-01

Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

First Implementation of a Two-Stage DC-DC Conversion Powering Scheme for the CMS Phase-2 Outer Tracker

CERN Document Server

Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Pauls, Alexander Josef; Preuten, Marius; Rauch, Max Philip; Wangelik, Frederik; Wlochal, Michael

2017-01-01

The 2S silicon strip modules for the CMS Phase-2 tracker upgrade will require two operating voltages. These will be provided via a two-step DC-DC conversion powering scheme, in which one DC-DC converter delivers 2.5\\,V while the second DC-DC converter receives 2.5\\,V at its input and converts it to 1.2\\,V. The DC-DC converters will be mounted on a flex PCB, the service hybrid, together with an opto-electrical converter module (VTRx+) and a serializer (LP-GBT). The service hybrid will be mounted directly on the 2S module. A prototype service hybrid has been developed and its performance has been evaluated, including radiative and conductive noise emissions, and efficiency. In addition system tests with a prototype module have been performed. In this report the service hybrid will be described and the test results will be summarized.

A suitable model plant for control of the set fuel cell-DC/DC converter

Energy Technology Data Exchange (ETDEWEB)

Andujar, J.M.; Segura, F.; Vasallo, M.J. [Departamento de Ingenieria Electronica, Sistemas Informaticos y Automatica, E.P.S. La Rabida, Universidad de Huelva, Ctra. Huelva - Palos de la Frontera, S/N, 21819 La Rabida - Palos de la Frontera Huelva (Spain)

2008-04-15

In this work a state and transfer function model of the set made up of a proton exchange membrane (PEM) fuel cell and a DC/DC converter is developed. The set is modelled as a plant controlled by the converter duty cycle. In addition to allow setting the plant operating point at any point of its characteristic curve (two interesting points are maximum efficiency and maximum power points), this approach also allows the connection of the fuel cell to other energy generation and storage devices, given that, as they all usually share a single DC bus, a thorough control of the interconnected devices is required. First, the state and transfer function models of the fuel cell and the converter are obtained. Then, both models are related in order to achieve the fuel cell+DC/DC converter set (plant) model. The results of the theoretical developments are validated by simulation on a real fuel cell model. (author)

Salud y condiciones de trabajo en trabajadores mayores

Directory of Open Access Journals (Sweden)

Elena Ordaz Castillo

2015-09-01

Full Text Available Introducción: En los últimos años, la población española ha experimentado un crecimiento acelerado de personas mayores. Las previsiones demográficas a corto-medio plazo describen un importante predominio de trabajadores mayores en el mercado laboral. Objetivos: Identificar las diferencias según dos grupos de edad (55 años en la percepción de las condiciones de trabajo y salud de la población trabajadora española. Metodología: Las diferencias entre los dos grupos de edad se analizaron a partir de indicadores de condiciones de trabajo y de salud pertenecientes a la VII Encuesta Nacional de Condiciones de Trabajo del Instituto de Seguridad e Higiene en el Trabajo (VII_ENCT. El análisis consistió en el cálculo de las prevalencias y la odds ratio cruda-ORc y ajustada por sexo con su correspondiente intervalo del confianza al 95%. Resultados: El grupo de trabajadores más jóvenes presentan más riesgo de exposición a seis de los siete indicadores relacionados con las condiciones de trabajo (ruido, vibraciones, carga física, carga mental, autonomía y motivación. No obstante los trabajadores mayores tienen una peor percepción de su estado de salud (ORa= 2,06 [1,75-2,42] y presentan en mayor medida problemas de salud que si bien les conducen a la visita médica más frecuentemente los relacionan menos con su actividad laboral. Conclusiones: A tenor de los resultados, los trabajadores de 55 años y más refieren tener menos quejas respecto a sus condiciones laborales e incluso se sienten más autónomos y motivados. Es el deterioro físico y mental la principal limitación que encuentran estos trabajadores a la hora de ejercer sus tareas. Sería recomendable establecer políticas de promoción de la salud dentro de las empresas para mejorar los indicadores de salud y promover el envejecimiento activo de la población trabajadora española.

La sobrecarga de los cuidadores informales de personas mayores dependientes en Medina del Campo

OpenAIRE

Archiles Diez, Eva

2016-01-01

Los cuidadores informales de personas mayores dependientes constituyen un capital social de vital importancia. El hecho de cuidar a un familiar mayor dependiente, es un fenómeno cada vez más extendido que se está convirtiendo en una experiencia común en la vida familiar de muchas personas, por ello estos cuidadores suponen un capital social de enorme importancia. Este capital social, permite que las personas mayores dependientes que permanecen en el domicilio, puedan disfrutar de un nivel de ...

Research of digital controlled DC/DC converter based on STC12C5410AD

Science.gov (United States)

Chen, Dan-Jiang; Jin, Xin; Xiao, Zhi-Hong

2010-02-01

In order to study application of digital control technology on DC/DC converter, principle of increment mode PID control algorithm was analyzed in the paper. Then, a SCM named STC12C5410AD was introduced with its internal resources and characteristics. The PID control algorithm can be implemented easily based on it. The output of PID control was used to change the value of a variable that is 255 times than duty cycle, and this reduced the error of calculation. The valid of the presented algorithm was verified by an experiment for a BUCK DC/DC converter. The experimental results indicated that output voltage of the BUCK converter is stable with low ripple.

On-grid and Off-grid Operation of Multi-Input Single-Output DC/DC Converter based Fuel Cell Generation System

Directory of Open Access Journals (Sweden)

Noroozian

2009-06-01

Full Text Available This paper presents the modeling and simulation of a proton exchange membrane fuel cell (PEMFC generation system for off-grid and on-grid operation and configuration. A fuel cell DG system consists of a fuel cell power plant, a DC/DC converter and a DC/AC inverter. The dynamic model for fuel cell array and its power electronic interfacing are presented also a multi-input single output (MISO DC/DC converter and its control scheme is proposed and analyzed. This DC/DC converter is capable of interfacing fuel cell arrays to the DC/AC inverter. Also the mathematical model of the inverter is obtained by using average technique. Then the novel control strategy of DC/AC inverter for different operating conditions is demonstrated. The simulation results show the effectiveness of the suggested control systems under both on-grid and off-grid operation modes.

Tele-asistencia y tele-alarma para adultos mayores: experiencias preliminares en Mexico

Directory of Open Access Journals (Sweden)

Liliana Giraldo-Rodriguez

2013-08-01

Full Text Available OBJETIVO Analizar el efecto de un programa piloto de tele-asistencia y tele-alarma en la autopercepción del estado de salud de los adultos mayores y conocer la satisfacción y aceptación del programa. METODOS Estudio transversal que incluyó entrevistas a 378 adultos mayores, 294 cuidadores/familiares y 53 profesionales de la salud, realizado en la Ciudad de México en 2010. Variables sociodemográficas, de autopercepción del estado de salud, satisfacción y aceptación del programa se obtuvieron por medio de cuestionario estandarizado. Se realizó análisis descriptivo y se utilizaron pruebas no paramétricas. RESULTADOS Se observaron efectos significativos en la autopercepción del estado de salud, 6,17 (DE 17,9 p < 0,05 puntos por encima de la media. El programa tuvo una buena aceptación por parte de los adultos mayores, de sus cuidadores familiares y de los profesionales de la salud. CONCLUSIONES El programa contribuye a mantener o mejorar la calidad de vida, permite la atención preventiva y es un medio ideal para dar apoyo psicosocial a los adultos mayores.

RF-superimposed DC and pulsed DC sputtering for deposition of transparent conductive oxides

International Nuclear Information System (INIS)

Stowell, Michael; Mueller, Joachim; Ruske, Manfred; Lutz, Mark; Linz, Thomas

2007-01-01

Transparent conductive oxide films are widely used materials for electronic applications such as flat panel displays and solar cells. The superposition of DC and pulsed DC power by a certain fraction of RF power was applied to deposit indium tin oxide films. This technique allows an additional tuning of different parameters relevant to film growth, and yields high quality films even under kinetically limited conditions. A long-term stable RF/DC process could be realized by using different combinations of standard power supply components, which includes a fully reliable arc handling system for both the RF and DC generators. The effectiveness of the arc handling system is illustrated by the current and voltage behavior recorded for actual arcing events. The resistivity of indium tin oxide films is strongly influenced by the respective sputtering mode. The best resistivity values of 145-148 μΩ cm were obtained by RF-superimposed pulsed DC sputtering at a pulse frequency between 100 and 200 kHz and a substrate temperature as low as 140 deg. C. In addition, the films were extremely smooth with a surface roughness of 1-2.5 nm

IEEE guide for planning of pre-operational testing programs for class 1E power systems for nuclear-power generating stations

International Nuclear Information System (INIS)

Anon.

1976-01-01

The Institute of Electrical and Electronics Engineers (IEEE) guide for pre-operational testing of Class 1E power systems for nuclear-power generating stations is presented. The guidelines apply to power systems both ac and dc supplies but not to the equipment which utilizes the ac and dc power. The pre-operational tests are performed after appropriate construction tests

The application of standardized control and interface circuits to three dc to dc power converters.

Science.gov (United States)

Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.

1973-01-01

Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

Design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters

CERN Document Server

Cravero, Jean-Marc

2013-01-01

This technical report presents the design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters. The power stage is based on a half bridge series resonant converter in Discontinuous Conduction Mode (DCM). This simple and robust topology allows obtaining a current source behavior with a low switching losses power stage. The associated control stage is implemented using a commercial controller which has differenti nternal circuits that allows a high integration of the converter control system. The report presents the design and tuning criteria for the DC-DC converter, including the power stage and the control system.

Actividad física, ejercicio físico y adulto mayor

OpenAIRE

Ozols R., Ma Antonieta; Corrales Araya, Ma Antonieta

2017-01-01

Se ha comprobado que la actividad física y el ejercicio mejoran la calidad de vida de las personas mayores. Las investigaciones han encontrado progresos en el plano físico, emocional y social. Una de las organizaciones que está promoviendo estilos de vida saludables es la Organización Mundial de la Salud, que ha enfocado su atención en todas las etapas de la vida: desde la niñez hasta la edad adulta mayor.

Analysis of DC/DC Converter Efficiency for Energy Storage System Based on Bidirectional Fuel Cells

DEFF Research Database (Denmark)

Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

2013-01-01

interface to the grid. In power electronics, the converter efficiency is characterized at fixed operating voltage for various output power. This type of characterization is not suitable for fuel cells, since as the power from the fuel cell increases, the cell voltage decreases. This paper analyses how......Renewable energy sources are fluctuating depending on the availability of the energy source. For this reason, energy storage is becoming more important and bidirectional fuel cells represent an attractive technology. Fuel cells require highcurrent low-voltage dc-dc or dc-ac converters as power...... the fuel cell I-V characteristics influences the power electronics converter efficiency and their consequence on the overall system. A loaddependent efficiency curve is presented based on experimental results from a 6 kW dc-dc converter prototype including the most suitable control strategy which maximizes...

Design and Implementation of Digital Current Mode Controller for DC-DC Converters

DEFF Research Database (Denmark)

Taeed, Fazel

to be regulated by a closed-loop controller. The Peak Current Mode Control (PCMC) is one of the most promising control methods for dc-dc converters. It has been known for high bandwidth (speed), and inherent current protection. Increasing the controller bandwidth decreases the output filter size and cost. Analog...

Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface

International Nuclear Information System (INIS)

Adib, Ehsan; Farzanehfard, Hosein

2009-01-01

In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis.

Design and modelling of high gain DC-DC converters for fuel cell hybrid electric vehicles

Science.gov (United States)

Elangovan, D.; Karthigeyan, V.; Subhanu, B.; Ashwin, M.; Arunkumar, G.

2017-11-01

Transportation (Diesel and petrol internal combustion engine vehicles) approximately contributes to 25.5% of total CO2 emission. Thus diesel and petrol engine vehicles are the most dominant contributors of CO2 emission which leads global warming which causes climate change. The problem of CO2 emission and global warming can be reduced by focusing on renewable energy vehicles. Out of the available renewable energy sources fuel cell is the only source which has reasonable efficiency and can be used in vehicles. But the main disadvantage of fuel cell is its slow response time. So energy storage systems like batteries and super capacitors are used in parallel with the fuel cell. Fuel cell is used during steady state vehicle operation while during transient conditions like starting, acceleration and braking batteries and super capacitors can supply or absorb energy. In this paper a unidirectional fuel cell DC-DC converter and bidirectional energy storage system DC-DC converter is proposed, which can interface dc sources at different voltage levels to the dc bus and also it can independently control the power flow from each energy source to the dc bus and vice versa. The proposed converters are designed and simulated using PSIM version 9.1.1 and gate pulse pattern, input and output voltage waveforms of the converters for steady state operation are studied.

Modelling and Control Design of a Dual Buck-Boost AC/DC Converter Used in the DC Nano-Grid

DEFF Research Database (Denmark)

Wu, Weimin; Liu, Yuan; Wang, Houqing

2016-01-01

Due to widely used DC characterized loads and more distributed power generation sources, the DC Nano-grid becomes more and more popular and seen as an alternative to the AC-grid in future. For the safety considerations, the DC Nano-grid should provide reliable grounding for the residential loads...... like the low voltage AC power system. In this paper, a dual Buck-Boost AC/DC converter for use in the united grounding configuration based DC Nano-grid with three terminal outputs is proposed. It will be much easy to construct an efficient DC Nano-grid based on the existing low AC power system by using...

Magnetically integrated high step-up resonant DC-DC converter for distributed photovoltaic systems

DEFF Research Database (Denmark)

Vinnikov, Dmitri; Chub, Andrii; Liivik, Elizaveta

2017-01-01

In this paper magnetically integrated resonant single-switch quasi-Z-source DC-DC converter is evaluated as a candidate topology for the low-cost photovoltaic microconverter. The derivation of the topology and its basic operation principle are explained. Generalized design guidelines...

Drilling history core hole DC-4

International Nuclear Information System (INIS)

1978-12-01

Core hole DC-4 was completed at a depth of 3998 feet in December, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Sicsson, Inc. furnished the engineering, daily supervision of the cable tool and core drilling activities, and geological core logging for DC-4. Core hole DC-4 is located on the Hanford Site about 3 miles east of the Yakima Barricade and approximately 103 feet southwest of rotary hole DC-5, which was completed to 3990 feet in February, 1978. Hanford Site coordinates reported for hole DC-4 are north 49,385.62 feet and west 85,207.63 feet, and Washington State coordinates are north 454,468.73 feet and east 2,209,990.87 feet. No elevation survey is available for hole DC-4, but it is approximately 745 feet above mean sea level based upon the survey of hole DC-5, which has a reported elevation of 745.16 feet on the top of the 3-inch flange. The purpose of core hole DC-4 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing, cross-hole seismic shear, and pressure wave velocity studies with rotary hole DC-5. Hole DC-4 was drilled through the overburden into basalt bedrock by cable tool methods (0-623 feet) and continuously cored through the final interval (623 to 3998 feet).Core recovery was 95.8 percent of the total footage cored

OPTIMALISASI PELAKSANAAN KURIKULUM SISTEM MAYOR-MINOR PROGRAM PENDIDIKAN SARJANA INSTITUT PERTANIAN BOGOR

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Sutoro Sutoro

2016-09-01

Full Text Available This study aims to 1 evaluate the implementation of major-minor curriculum system in IPB Undergraduate Program, 2 identify factors leading to less optimized implementation of the major-minor curriculum system in IPB Undergraduate Program and 3 design strategies to optimize the implementation of the major-minor curriculum system in IPB Undergraduate Program. Analytical Hierarchy Process was utilized as the method of study. The results showed that the implementation of the major-minor curriculum system in IPB Undergraduate Program is still considered to be less optimal. Factors influencing the implementation of the major-minor curriculum system in IPB Undergraduate Program, according to its priority, include: 1 the availability of competent and committed teaching staffs, 2 the availability of adequate lecturing facilities and infrastructure, 3 the availability of lecture schedule to accommodate students who choose minor curriculum, and 4 the availability of reliable and IT-based Academic Information System (SIMAK. Strategies to optimize the implementation of major-minor curriculum system in IPB Undergraduate Program, according to its priority, include; 1 improving the competence and commitment of teaching and educational staffs, 2 increasing the commitment of departments and faculties to facilitate the fulfillment of minor  curriculum schedules, 3 providing adequate facilities and infrastructure to implement the major and minor curriculum system, and 4 providing lecture schedules that can accommodate the needs of students who choose minor curriculum.Keywords: analytical hierarchy process, optimization, major-minor curriculum systemABSTRAKPenelitian ini bertujuan 1 mengevaluasi pelaksanaan kurikulum sistem mayor-minor pada Program Pendidikan Sarjana IPB, 2 mengidentifikasi faktor-faktor yang menyebabkan kurang optimalnya pelaksanaan kurikulum sistem mayor-minor pada Program Pendidikan Sarjana IPB dan 3 merancang strategi untuk mengoptimalkan

Estimulación de la Inteligencia Emocional en mayores: El programa PECI-PM

Directory of Open Access Journals (Sweden)

Mª del Carmen Pérez-Fuentes

2014-12-01

Full Text Available El programa de Estimulación Cognitiva e Inteligencia Emocional para personas mayores (PECI-PM, combina técnicas de estimulación cognitiva con la intervención y estimulación sobre aspectos relacionados con la inteligencia emocional. El objetivo del presente trabajo es analizar los resultados obtenidos en inteligencia emocional, tras la primera fase de implementación del PECI-PM. Para ello, se contó con una muestra de 28 usuarios del programa, que habían completado 20 sesiones y participado en las dos evaluaciones (pre-post. La Inteligencia Emocional se evaluó, antes y después de la intervención, mediante el Inventario Breve de Inteligencia Emocional para Mayores (EQ-i-M20. Tras la intervención con el PECI-PM, se observa una mejora, en la mayoría de las dimensiones de inteligencia emocional (Intrapersonal, Interpersonal, Adaptabilidad y Estado de Ánimo. En la dimensión Manejo del Estrés, no se observa un cambio en las puntuaciones obtenidas tras la intervención, lo que lleva a replantear el peso de esta dimensión en la inteligencia emocional de la población mayor. Por otro lado, destaca el papel de la dimensión Interpersonal, que correlaciona significativamente con otros factores de la inteligencia emocional (Intrapersonal y Adaptabilidad, en mayores.

Nuevos mayores, viejas brechas: TIC, desigualdad y bienestar en la tercera edad en Italia

Directory of Open Access Journals (Sweden)

Piermarco Aroldi

2015-07-01

Full Text Available Italia parece tener un retraso de unos diez años en comparación con otros países más digitalizados, tanto en el uso de las TIC por las personas mayores como en el estudio de la relación entre las TIC y los mayores de 65 años. Por ello, se hace urgente examinar los factores que influyen en la adopción de las tecnologías por los mayores y la capacidad real de estas para proporcionar recursos culturales e interactivos, útiles para mejorar el envejecimiento activo y mejorar su calidad de vida en salud y vida social. Este trabajo describe los principales resultados de un estudio que involucró a 900 italianos de 65 a 74 años, en el marco de un proyecto nacional de investigación sobre el envejecimiento activo. El estudio indaga en las características sociodemográficas de los mayores italianos usuarios de Internet y en los factores que influyen en el uso de las TIC. Los resultados evidencian que existe una fuerte brecha digital entre los mayores, influenciada por el contexto económico y cultural. En cuanto al envejecimiento activo, se demuestra que los mayores altamente digitales presentan una mejor vida saludable en su envejecimiento, sin poderse concluir que el uso de las TIC garantice la inclusión y participación.

DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

Science.gov (United States)

Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi

2013-06-01

Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.

Wide Temperature Range DC-DC Boost Converters for Command/Control/Drive Electronics, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We shall develop wide temperature range DC-DC boost converters that can be fabricated using commercial CMOS foundries. The boost converters will increase the low...

DC Microgrids—Part II

DEFF Research Database (Denmark)

Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez

2016-01-01

distribution applications such as traction, telecom, vehicular and distributed power systems can be classified under DC MG framework and ongoing development and expansion of the field is largely influenced by concepts used over there. This paper aims firstly to shed light on the practical design aspects of DC...... MG technology concerning typical power hardware topologies and their suitability for different emerging smart grid applications. Then, an overview of the state of the art in DC MG protection and grounding is provided. Owing to the fact that there is no zero current crossing, an arc that appears upon...

Selection of DC/DC converter for offshore wind farms with MVDC power collection

DEFF Research Database (Denmark)

Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

2017-01-01

Four DC/DC converters are analyzed and compared with respects to availability, efficiency, ratings, repair costs and power density. Intended application is offshore wind farms with MVDC power collection. The selected topology is a new series resonant converter, which offers 99% efficiency across...

Personas mayores y nuevas tecnologias. Propuesta de intervencion con dispositivos moviles

OpenAIRE

Pereira García, César Gualter

2014-01-01

En el presente trabajo, se proponen los cauces sobre los que llevar a cabo, una intervención psicopedagógica, interrelacionando tres elementos definidos por unas características concretas a contemplar de manera particular; las personas mayores, las características de la sociedad actual, y las tecnologías de la información y comunicación. El constatado aumento de la población, observado este de manera significativa en las personas de mayor edad, exige la implementación de contin...

Integrated Three-Port DC-DC Converter for Photovoltaic (PV) Battery Stand-alone Systems

DEFF Research Database (Denmark)

Ouyang, Ziwei; Andersen, Michael A. E.

2016-01-01

of solar energy. Moreover, a novel transformer configuration enables variable turns ratio controlled by the phase between the two current excitations subjected to the primary windings, allowing a wider input/output range. 1 kW experimental prototype has been built to demonstrate a wellmanaged power flow......Several power sources such as PV solar arrays and battery are often used to manage the power flow for a photovoltaic (PV) based stand-alone power system due to the fluctuation nature of solar energy resource, and deliver a continuous power to the users in an appropriate form. Traditionally, three...... different single-input single-output (SISO) dc/dc converters would have been used. To reduce the cost and improve the power density of the system, an integrated three-port isolated dc/dc converter is proposed in this paper. It can realize all functions of the energy delivery due to the fluctuation nature...

Integrating DC/DC Conversion with Possible Reconfiguration within Submodule Solar Photovoltaic Systems

Science.gov (United States)

Huang, Peter Jen-Hung

This research first proposes a method to merge photovoltaic (PV) cells or PV panels within the internal components DC-DC converters. The purpose of this merged structure is to reconfigure the PV modules between series and parallel connections using high switching frequencies (hundreds of kHz). This leads to multi-levels of voltages and currents that become applied to the output filter of the converter. Further, this research introduces a concept of a switching cell that utilizes the reconfiguration of series and parallel connections in DC-DC converters. The switching occurs at high switching frequency and the switches can be integrated to be within the solar panels or in between the solar cells. The concept is generalized and applied to basic buck and boost topologies. As examples of the new types of converters: reconfigurable PV-buck and PV-boost converter topologies are presented. It is also possible to create other reconfigurable power converters: non-isolated and isolated topologies. Analysis, simulation and experimental verification for the reconfigurable PV-buck and PV-boost converters are presented extensively to illustrate proof of concept. Benefits and drawbacks of the new approach are discussed. The second part of this research proposes to utilize the internal solar cell capacitance and internal solar module wire parasitic inductances to replace the input capacitor and filter inductor in boost derived DC-DC converters for energy harvesting applications. High switching frequency (MHz) hard switched and resonant boost converters are proposed. Their analysis, simulation and experimental prototypes are presented. A specific proof-of-concept application is especially tested for foldable PV panels, which are known for their high internal wire inductance. The experimental converters successfully boost solar module voltage without adding any external input capacitance or filter inductor. Benefits and drawbacks of new proposed PV submodule integrated boost

Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface

Energy Technology Data Exchange (ETDEWEB)

Adib, Ehsan; Farzanehfard, Hosein [Dept. of Electrical and Computer Engineering, Isfahan Univ. of Technology (Iran)

2009-12-15

In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis. (author)

Retrospective evaluation of early and aggressive decompressive craniectomy (DC) for severe head injury. Was that DC necessary?

International Nuclear Information System (INIS)

Hagihara, Yasushi; Ueno, Masato; Mizushima, Yasuaki; Matsuoka, Tetsuya

2011-01-01

Recently, decompressive craniectomy (DC) for refractory intracranial hypertension (IH) has been widely reevaluated, and many researchers support the advantages of early and aggressive DC in the management of severe head trauma. We too applied DC in the early stages of IH, and confirmed its favorable results compared to those of the standard treatment. In patients with evacuate masses (EM), DC was determined based on the intraoperative condition of the brain parenchyma; in those without EM, intracranial pressure (ICP) ≥30 mmHg was considered the criterion for DC. However, in some cases, the expected brain edema (BE) was absent after DC, and DC seemed unnecessary on retrospection. Here, the effectiveness of DC performed at our hospital and its predictive factors were investigated. Of the 26 DCs performed in the past 3.5 years, 9 were ineffective because the expected BEs were absent on postoperative computed tomography. In those 9 cases, the Glasgow coma scale (GCS) scores and D-dimer of fibrinogen degradation product (FDP-DD) were significantly higher and lower, respectively, than those of the control group. Patients with EM showed similar trends regarding the GCS score and FDP-DD, both of which are probable indicators of BE. In patients without EM, the GCS score and FDP-DD were normal, but their base excess at admission was significantly low with increased ICP, requiring DC. GCS score and FDP-DD may represent the extent of mechanically damaged brain, and this may explain their relation with DC effectiveness in patients with EM. In patients without EM and with mild brain damage, base excess that reflects the respiratory or circulatory disorder should be the predictor for BE. (author)

Future electoral impacts of having a female mayor

Directory of Open Access Journals (Sweden)

Paulo Arvate

2017-08-01

Full Text Available We explore an electoral quasi-experiment where a woman nearly won or lost to a man in a mayoral election. Our data combines municipal Brazilian election results, which occur every four years, with municipal level votes for female and male candidates in state and federal deputy elections, whose districts are larger than the municipalities. Our results show that when voters are exposed to a female leader, the relative number of votes given to female candidates increases. This result depends on the political environment in which the exposure occurs. These effects on the electorate's response tend to be stronger: 01. in municipalities where there is a previous higher proportion of female councilors, and 02. when the mayors have higher education levels. Our results provide evidence that the observed electorate's gender preferences in politics are alterable, but that policy interventions aimed to equalize access will be more effective if they are targeted at underrepresented populations that have the correct skill requirements to perform in leadership positions.

Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

Directory of Open Access Journals (Sweden)

Mircea R. Stan

2013-07-01

Full Text Available The increasing popularity of DVFS (dynamic voltage frequency scaling schemes for portable low power applications demands highly efficient on-chip DC-DC converters. The primary aim of this work is to enable increased efficiency of on-chip DC-DC conversion for near-threshold operation of multicore chips. The idea is to supply nominal (high off-chip voltage to the cores which are then “voltage-stacked” to generate the near-threshold (low voltages based on Kirchhoff’s voltage law through charge recycling. However, the effectiveness of this implicit down-conversion is affected by the current imbalance among the cores. The paper presents a design methodology and optimization strategy for highly efficient charge recycling on-chip regulation using a push-pull switched capacitor (SC circuit. A dual-boundary hysteretic feedback control circuit has been designed for stacked loads. A stacked-voltage domain with its self-regulation capability combined with a SC converter has shown average efficiency of 78%–93% for 2:1 down-conversion with ILoad (max of 200 mA and workload imbalance varying from 0–100%.

Hierarchical Control for Multiple DC-Microgrids Clusters

DEFF Research Database (Denmark)

Shafiee, Qobad; Dragicevic, Tomislav; Vasquez, Juan Carlos

2014-01-01

DC microgrids (MGs) have gained research interest during the recent years because of many potential advantages as compared to the ac system. To ensure reliable operation of a low-voltage dc MG as well as its intelligent operation with the other DC MGs, a hierarchical control is proposed in this p......DC microgrids (MGs) have gained research interest during the recent years because of many potential advantages as compared to the ac system. To ensure reliable operation of a low-voltage dc MG as well as its intelligent operation with the other DC MGs, a hierarchical control is proposed...

High-Efficiency High Step-Up DC-DC Converter with Dual Coupled Inductors for Grid-Connected Photovoltaic Systems

DEFF Research Database (Denmark)

Forouzesh, Mojtaba; Shen, Yanfeng; Siwakoti, Yam Prasad

2018-01-01

with a common ground connection of the input and output make the proposed topology a proper candidate for a transformer-less grid connected photovoltaic systems. The operating performance, analysis and mathematical derivations of the proposed dc-dc converter have been demonstrated in the paper. Moreover......This paper introduces a non-isolated high step-up dc-dc converter with dual coupled inductors suitable for distributed generation applications. By implementing an input parallel connection, the proposed dc-dc structure inherits shared input current with low ripple, which also requires small...... capacitive filter at its input. Moreover, this topology can reach high voltage gain by using dual coupled inductors in series connection at the output stage. The proposed converter uses active clamp circuits with a shared clamp capacitor for the main switches. In addition to the active clamp circuit...

Design and Implementation of Anti-windup PI Control on DC-DC Bidirectional Converter for Hybrid Vehicle Applications

Directory of Open Access Journals (Sweden)

Muh. Zakiyullah Romdlony

2012-07-01

Full Text Available Well-regulated DC bus voltage is the important point to guarantee the power demand in hybrid vehicle applications. Voltage regulation can be achieved with control method that build switching signal on DC-DC converter. This paper describes design and small scale experimental results of bus voltage regulation control of the DC-DC bidirectional converter with battery and supercapacitor as energy source. The control system consists of two control loops, the outer loop that get DC bus voltage feedback using PI anti-windup back calculation control method. This outer loop will generate a reference current for the inner loop that implement hysteresis control. The inner control loop will compare that reference curent with the source current obtained from the current sensor. Simulation and experimental results show that bus voltage is well-regulated under the load changes with 1% voltage ripple.

Light-weight DC to very high voltage DC converter

Energy Technology Data Exchange (ETDEWEB)

Druce, Robert L. (Union City, CA); Kirbie, Hugh C. (Dublin, CA); Newton, Mark A. (Livermore, CA)

1998-01-01

A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current.

Current Mode Control for LLC Series Resonant DC-to-DC Converters

OpenAIRE

Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi

2015-01-01

Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a...

Significado de la calidad de vida del adulto mayor para sí mismo y para su familia

Directory of Open Access Journals (Sweden)

Martha Vera

2007-09-01

Full Text Available Objetivo: Comprender el significado que la expresión lingüística ‘calidad de vida del adulto mayor’ tiene para el adulto mayor y para su familia. Diseño: Estudio cualitativo, descriptivo, interpretativo - comprensivo, fundamentado en la Teoría de las Representaciones Sociales. Lugar: Asentamiento Humano Laura Caller, en Los Olivos. Participantes: Adultos mayores y sus respectivos grupos familiares. Métodos: Las técnicas e instrumentos utilizados fueron la observación, entrevista a profundidad y grupos focales; guía de observación y dos cuestionarios con ocho preguntas norteadoras, previamente validados. Principales medidas de resultados: Significado de calidad de vida para el adulto mayor y para la familia. Resultados: Participaron dieciséis adultos mayores con sus respectivos grupos familiares, entre 2004 y 2006. Los discursos a través de la ‘objetivación’ y el ‘anclaje’ y los análisis general, ideográfico-axial y nomotético-selectivo permitieron la emergencia de cuatro representaciones sociales: a conocimiento sobre la vejez y ser un adulto mayor; b elementos principales y secundarios del significado de calidad de vida del adulto mayor; c valores y actitudes del adulto mayor y familia sobre la calidad de vida; y, d necesidades del adulto mayor como ser social y la calidad de vida. Conclusiones: Para el adulto mayor, calidad de vida significa tener paz y tranquilidad, ser cuidado y protegido por la familia con dignidad, amor y respeto, y tener satisfechas como ser social sus necesidades de libre expresión, decisión, comunicación e información. Para la familia, que el adulto mayor satisfaga sus necesidades de alimentación, vestido, higiene y vivienda.

Valoración funcional del adulto mayor relacionado con el abandono familiar.

Directory of Open Access Journals (Sweden)

Jenny Fernanda Villarroel Vargas

2017-03-01

Full Text Available Introducción: Se estima que entre el 2000 al 2050 la población mundial envejecida ascenderá del 11% al 22 %, con ello el incremento de las diversas enfermedades o trastornos propios de la edad. Objetivo: Establecer la relación entre capacidad funcional del adulto mayor con el abandono familiar en el barrio La Calera Centro, Latacunga, 2015-2016. Métodos: Se realizó un estudio observacional descriptivo de corte trasversal, donde previo consentimiento informado participaron 70 adultos mayores, a quienes se les aplicó escalas para valoración de la capacidad funcional, así como la encuesta para valorar abandono familiar y aspectos sociodemográficos de la población. Para el análisis estadístico se utilizó el test de Chi Cuadrado de Pearson con un nivel de significancia del 0,05. Resultados: Se reportó el abandono en el 75,7% de los adultos mayores y tuvo significancia con respecto a la capacidad funcional y la estructura familiar (p=0,002. Hubo relación  entre capacidad funcional y abandono familiar, así como también predominio de los adultos mayores entre los 65 a 74 años, sexo femenino, sin ninguna actividad laboral y analfabetos. Hubo relación significativa entre capacidad funcional, edades geriátricas y ocupación; y de igual manera entre la estructura familiar y el abandono. La capacidad funcional y la estructura familiar fueron factores asociados al abandono.    Conclusiones: La dependencia del adulto mayor condicionó a diferentes tipos de maltrato, destacando el abandono familiar.

Tipología de compradores online mayores de 55 años

Directory of Open Access Journals (Sweden)

Ángel F. Villarejo-Ramos

2015-12-01

Full Text Available La edad se considera una de las variables determinantes del riesgo de exclusión social de la población, especialmente con relación al uso de las nuevas tecnologías en general y de Internet en particular. Esto ha incidido en una creciente preocupación por el estudio del colectivo de mayores de 55 años y sus peculiaridades en lo relativo al acceso, uso y aprovechamiento de las TIC (Tecnologías de la Información y la Comunicación. Sin embargo, los esfuerzos se han centrado, mayoritariamente, en el análisis del grupo de mayores como algo homogéneo, lo que ha llevado a establecer sus perfiles de comportamiento en comparación con el de otros grupos de edad. En esta investigación, con una muestra útil de 595 mayores, partimos de la consideración del colectivo como grupo heterogéneo, con distintas características y condiciones de uso de Internet, y proponemos un modelo de clases latentes que nos permite establecer tres perfiles de mayores internautas en función de la utilización de un servicio avanzado de Internet, la compra online.

Floating high step-down stacked dc-dc converter based on buck-boost cells

NARCIS (Netherlands)

Tibola, G.; Duarte, J.L.; Blinov, A.

2015-01-01

In some high power dc-dc applications, where high voltage is present, a converter with high step-down ratio is required in order to provide an isolated low power auxiliary supply. This requirement represents a challenge and many topologies are currently being researched. The analysis of a

UNJUK KERJA PENGUBAH TEGANGAN DC-DC TOPOLOGI BOOST DENGAN NILAI INDUKTANSI DAN KAPASITANSI YANG DIOPTIMASI PADA KEADAAN TRANSIEN

Directory of Open Access Journals (Sweden)

I Wayan Arta Wijaya

2009-05-01

Full Text Available Pengubah daya DC-DC topologi boost dapat menghasilkan tegangan yang lebih tinggi dari tegangan input dengan riak (ripple yang kecil dan efisiensi yang cukup tinggi. Nilai dari sebuah induktansi dan kapasitansi dari pengubah daya DC-DC dengan menggunakan topologi boost dioptimalkan menggunakan analisa transien. Fungsi ini diatur berdasarkan pada analisa dari pengubah daya selama kondisi transien. Nilai induktansi dan kapasitansi yang telah dioptimalkan dengan perhitungan dibandingkan dalam simulasi pada pengubah daya DC-DC dan hasilnya akan dibuktikan dengan menggunakan hasil percobaan. Nilai optimal untuk kapasitor dan induktor pada frekuensi 666,7 Hz, siklus kerja (duty cycle 66,7 %, resistansi output 36 Ώ dan tegangan input 12 volt adalah 1038 μF dan 11,9 mH

Rhesus macaque and chimpanzee DC-SIGN act as HIV/SIV gp120 trans-receptors, similar to human DC-SIGN

NARCIS (Netherlands)

Geijtenbeek, T. B.; Koopman, G.; van Duijnhoven, G. C.; van Vliet, S. J.; van Schijndel, A. C.; Engering, A.; Heeney, J. L.; van Kooyk, Y.

2001-01-01

Dendritic cells (DC) have been implicated in the pathogenesis of both human and simian immunodeficiency viruses (HIV and SIV, respectively). The DC-specific HIV-1 trans-receptor DC-SIGN is thought to be essential for viral dissemination by DC. Abundant expression in lymphoid tissues also implies a

The Chaotic-Based Control of Three-Port Isolated Bidirectional DC/DC Converters for Electric and Hybrid Vehicles

Directory of Open Access Journals (Sweden)

Zheng Wang

2016-01-01

Full Text Available Three-port isolated (TPI bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.

A Markovian Approach Applied to Reliability Modeling of Bidirectional DC-DC Converters Used in PHEVs and Smart Grids

Directory of Open Access Journals (Sweden)

M. Khalilzadeh

2016-12-01

Full Text Available In this paper, a stochastic approach is proposed for reliability assessment of bidirectional DC-DC converters, including the fault-tolerant ones. This type of converters can be used in a smart DC grid, feeding DC loads such as home appliances and plug-in hybrid electric vehicles (PHEVs. The reliability of bidirectional DC-DC converters is of such an importance, due to the key role of the expected increasingly utilization of DC grids in modern Smart Grid. Markov processes are suggested for reliability modeling and consequently calculating the expected effective lifetime of bidirectional converters. A three-leg bidirectional interleaved converter using data of Toyota Prius 2012 hybrid electric vehicle is used as a case study. Besides, the influence of environment and ambient temperature on converter lifetime is studied. The impact of modeling the reliability of the converter and adding reliability constraints on the technical design procedure of the converter is also investigated. In order to investigate the effect of leg increase on the lifetime of the converter, single leg to five-leg interleave DC-DC converters are studied considering economical aspect and the results are extrapolated for six and seven-leg converters. The proposed method could be generalized so that the number of legs and input and output capacitors could be an arbitrary number.

PI and Fuzzy Control Strategies for High Voltage Output DC-DC Boost Power Converter - Hardware Implementation and Analysis

DEFF Research Database (Denmark)

Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Siano, Pierluigi

2016-01-01

This paper presents the control strategies by Proportional-Integral (P-I) and Fuzzy Logic (FL) for a DC-DC boost power converter for high output voltage configuration. Standard DC-DC converters are traditionally used for high voltage direct current (HVDC) power transmission systems. But, lack its...... converter with inbuilt voltage-lift technique and overcome the aforementioned deficiencies. Further, the control strategy is adapted based on proportional-integral (P-I) and fuzzy logic, closed-loop controller to regulate the outputs and ensure the performances. Complete hardware prototype of EHV converter...... performances in terms of efficiency, reduced transfer gain and increased cost with sensor units. Moreover, the internal self-parasitic components reduce the output voltage and efficiency of classical high voltage converters (HVC). This investigation focused on extra high-voltage (EHV) DC-DC boost power...

A Novel Quasi-SEPIC High-Voltage Boost DC-DC Converter

DEFF Research Database (Denmark)

Siwakoti, Yam Prasad; N. Soltani, Mohsen; Blaabjerg, Frede

2017-01-01

This paper proposes a modified coupled-inductor SEPIC dc-dc converter for low power and high voltage gain applications such as for piezoelectric drive systems. The converter uses the same components as of SEPIC converter with an additional diode. Compared to conventional topologies with similar...... voltage gain expression, the proposed topology uses less components to achieve same or even higher voltage gain. This helps to design a very compact and light weight converter with higher power density at lower cost. Due to brevity, the principle of operation, theoretical analysis and comparison supported...

Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc

International Nuclear Information System (INIS)

Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

2014-01-01

Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.

Light-weight DC to very high voltage DC converter

Science.gov (United States)

Druce, R.L.; Kirbie, H.C.; Newton, M.A.

1998-06-30

A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current. 1 fig.

The 25 kW resonant dc/dc power converter

Science.gov (United States)

Robson, R. R.

1983-01-01

The feasibility of processing 25-kW of power with a single, transistorized, series resonant converter stage was demonstrated by the successful design, development, fabrication, and testing of such a device which employs four Westinghouse D7ST transistors in a full-bridge configuration and operates from a 250-to-350 Vdc input bus. The unit has an overall worst-case efficiency of 93.5% at its full rated output of 1000 V and 25 A dc. A solid-state dc input circuit breaker and output-transient-current limiters are included in and integrated into the design. Full circuit details of the converter are presented along with the test data.

DC grid for home applications

Science.gov (United States)

Elangovan, D.; Archana, R.; Jayadeep, V. J.; Nithin, M.; Arunkumar, G.

2017-11-01

More than fifty percent Indian population do not have access to electricity in daily lives. The distance between the power generating stations and the distribution centers forms one of the main reasons for lack of electrification in rural and remote areas. Here lies the importance of decentralization of power generation through renewable energy resources. In the present world, electricity is predominantly powered by alternating current, but most day to day devices like LED lamps, computers and electrical vehicles, all run on DC power. By directly supplying DC to these loads, the number of power conversion stages was reduced, and overall system efficiency increases. Replacing existing AC network with DC is a humongous task, but with power electronic techniques, this project intends to implement DC grid at a household level in remote and rural areas. Proposed work was designed and simulated successfully for various loads amounting to 250 W through appropriate power electronic convertors. Maximum utilization of the renewable sources for domestic and commercial application was achieved with the proposed DC topology.

Mayores Universitarios en la Red University Senior Students on the Web

Directory of Open Access Journals (Sweden)

Felicidad Loscertales Abril

2011-10-01

Full Text Available Hoy día la relevancia de Internet es cada vez mayor en todos los ámbitos. Participar en la misma es fundamental para estar integrados socialmente. El aumento de la esperanza y la calidad de vida conllevan que los mayores activos supongan un volumen significativo de la población. En este trabajo se analiza el uso que personas mayores activas realizan de Internet, así como los principales beneficios o motivaciones de su utilización, y las barreras que encuentran aquéllos que no la utilizan. Se administró un cuestionario a personas inscritas en programas universitarios de mayores. Los resultados muestran que estos mayores universitarios se conectan a Internet frecuentemente, a diario o entre dos o tres veces por semana. Se destaca la relevancia de Internet para estar actualizados, contactar con la familia y los amigos, el uso académico, y consultar la prensa. La consideran fácil de utilizar aunque afirman que podrían vivir sin ella. Por otro lado, para los que no acceden a Internet no saber utilizarla es una de las principales barreras, si bien las personas que no la utilizan consideran que serían capaces de aprender. En su conjunto los datos animan a romper estereotipos negativos sobre los mayores y a no considerar a los mayores activos como personas incapaces o desconectadas de la Red sino a valorar positivamente los avances que realizan y la motivación por aprender.The Internet is increasingly prominent in all walks of life, and Web connection is a key factor in social integration. The rise in life expectancy and quality of life mean that our active seniors now represent a growing sector in society. This study analyses what senior citizens use the Internet for and why, as well as the main benefits of its usage and the perceived obstacles of those who are non-users. The results derive from a questionnaire completed by senior citizens enrolled on university courses for older people, and they show that university seniors frequently

Static and Dynamic Characteristics of DC-DC Converter Using a Digital Filter

Science.gov (United States)

Kurokawa, Fujio; Okamatsu, Masashi

This paper presents the regulation and dynamic characteristics of the dc-dc converter with digital PID control, the minimum phase FIR filter or the IIR filter, and then the design criterion to improve the dynamic characteristics is discussed. As a result, it is clarified that the DC-DC converter using the IIR filter method has superior performance characteristics. The regulation range is within 1.3%, the undershoot against the step change of the load is less than 2% and the transient time is less than 0.4ms with the IIR filter method. In this case, the switching frequency is 100kHz and the step change of the load R is from 50 Ω to 10 Ω. Further, the superior characteristics are obtained when the first gain, the second gain and the second cut-off frequency are relatively large, and the first cut-off frequency and the passing frequency are relatively low. Moreover, it is important that the gain strongly decreases at the second cut-off frequency because the upper band pass frequency range must be always less than half of the sampling frequency based on the sampling theory.

Relación entre masa ósea y agilidad en personas mayores

OpenAIRE

A. Gómez-Cabello; G. Vicente-Rodríguez; A. González-Agüero; I. Ara; J. A. Casajús

2010-01-01

El objetivo de este estudio fue analizar la asociación entre masa ósea y agilidad en personas mayores. Se evaluó a 223 participantes mayores de 65 años (64 hombres y 159 mujeres) de Zaragoza (España). Se midió el área, contenido (CMO) y densidad mineral ósea (DMO) en el cuerpo completo, columna lumbar y cadera mediante absorciometría fotónica dual de rayos X (...

Welcome by the Mayor of Valtetsi

Science.gov (United States)

Papanikolau, N.

Welcome by the Mayor of Valtetsi Mr. Chairman Ladies and Gentlemen The municipality of Valtetsi welcomes you and wishes success in your work. Arcadia is both a historical and modern region. Moreover, as a name it remained in the western culture recalling a harmonious and peaceful dream, a lost and desirable situation where the human being lived in balance with nature, a region where the person did not feel yet uprooted. For thousands of years the poetic voices retained vivid this eternal bucolic call of simplicity and accessible happiness. Gazing the starlit sky we will always see Kallisto, the daughter of Lykaona, king of Arcadia and her son Arcadian as they were both transformed in to the constellations Major and Minor Ursus because of the erotic libido of Jupiter and the jealousy of Hera. And we will always remember Centaurus Cheirona, the great schoolteacher of ancient heroes, who was the first to name the constellations according to mythology. Finally we would like to thank the patriot Mr. T. Tzioumi who returns to his beautiful village in Arcadia just like Antaios did. In the geographic place that inspired the arcadian ideal, such activities recall in the limelight Arcadia as was dreamed by Europe. Mr. Chairman, ladies and gentlemen, success in your scientific work. The Municipality of Valtetsi and I myself will be always next to you so that your stay at Arcadia will always remain vivid in your memory. Thank you. Nikos Papanikolaou Mayor of Valtetsi

Cansancio, cuidados y repercusiones en cuidadores informales de adultos mayores con enfermedades crónico degenerativas

Directory of Open Access Journals (Sweden)

María Asunción Vicente Ruiz

2016-08-01

Full Text Available Las enfermedades crónicas como diabetes, hipertensión, enfermedad cardiovascular, cáncer, pueden limitar la habilidad de los adultos mayores para ejecutar actividades de la vida diaria, generando cansancio o sobrecarga en los cuidadores. Objetivo: Determinar la relación que existe entre el cansancio, el cuidado y los efectos a la salud del cuidador. Metodología: Estudio cuantitativo y analítico. La muestra se conformó con 123 cuidadores familiares y 123 personas adultas con enfermedad crónico degenerativa. El tipo de muestreo fue no probabilístico. Resultados y Discusión: Se encontró asociación entre el cansancio y las repercusiones del cuidado (r=.438, p<.01, lo que sugiere que mayor cansancio en los cuidadores, mayores serán las repercusiones en la salud. Además correlación de los cuidados que presta el cuidador con las repercusiones en la salud del cuidador (r=.546, p<.01, así a mayor cantidad y complejidad de los cuidados, mayores serán las repercusiones que afecten el bienestar del cuidador. Los cuidados se relacionaron con el cansancio, se afirma que a mayor cantidad y complejidad del cuidado mayor cansancio percibe el cuidador (r=.109, p<.01. Conclusión: El cansancio en los cuidadores es elevado, está asociado a la sobrecarga del cuidado con serias repercusiones en la salud o bienestar y fundamenta las intervenciones interdisciplinarias futuras.

Cutting through the Hype: The Essential Guide to School Reform. Revised, Expanded, and Updated Edition

Science.gov (United States)

David, Jane L.; Cuban, Larry

2010-01-01

"Cutting Through the Hype: The Essential Guide to School Reform" is a revised, expanded, and updated version of the classic work by Jane L. David and Larry Cuban. It offers balanced analyses of 23 currently popular school reform strategies, from teacher performance pay and putting mayors in charge to turnaround schools and data-driven instruction.…

Prevalencia de hipertensión en adultos mayores de Costa Rica

Directory of Open Access Journals (Sweden)

Rosero-Bixby, Luis

2007-07-01

Full Text Available Este artículo estima la prevalencia de hipertensión (controlada y con o sin diagnóstico previo entre los adultos mayores costarricenses. Valora los problemas de medición y explora los factores asociados con la enfermedad. Se utilizan datos de una muestra nacional representativa del proyecto CRELES: “Costa Rica: Estudio de Longevidad y Envejecimiento Saludable”. Se realizaron dos mediciones de la presión arterial con monitores digitales a una muestra de 3000 adultos y se registró el auto reporte de la enfermedad y el uso de medicamentos antihipertensivos. La segunda medición resultó en valores significativamente menores tanto para la presión diastólica como para la sistólica. No se detectaron sesgos en la medición realizada por entrevistador ni por trimestre de trabajo de campo. El 59% de los adultos mayores del país sufre de hipertensión (HTA. La prevalencia es mayor entre las mujeres que entre los hombres. El 16% de todos los adultos mayores no tenían diagnóstico previo de HTA pero en nuestras mediciones resultaron con HTA. Los principales co-factores de HTA identificados en este artículo son: edad, estar asegurado, el índice de masa corporal, los antecedentes familiares, tener menos de 6 años de educación formal, ser fumador activo y consumir más de 3000 calorías al día.

DC-Compensated Current Transformer †

Science.gov (United States)

Ripka, Pavel; Draxler, Karel; Styblíková, Renata

2016-01-01

Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830

Reliability study of high gain DC-DC converters based on RRPP I-IIA ...

Indian Academy of Sciences (India)

J DIVYA NAVAMANI

2018-05-10

May 10, 2018 ... Energy Storage Modules (ESM), Propulsion Motor Mod- ules (PMM) and ... All Electric Ship (AES) is the best way to power all the loads in the ship ... also used to derive quadratic step down DC-DC converters. [6]. The attractive ...... Exhibition on Ecological Vehicles and Renewable Energies,. TamilNadu ...

Influence of DC arc jets on flow fields analyzed by an integrated numerical model for a DC-RF hybrid plasma

International Nuclear Information System (INIS)

Seo, Jun Ho; Park, Jin Myung; Hong, Sang Hee

2008-01-01

The influence of DC arc jets on the flow fields in a hybrid plasma torch is numerically analyzed by an integrated direct current-radio frequency (DC-RF) plasma model based on magneto-hydrodynamic formulations. The calculated results reveal that the increase in DC arc gas flow rate raises the axial flow velocity along the central column of the DC-RF hybrid plasma together with the enhanced backflow streams in the peripheral wall region. The temperature profiles on the torch exit plane are little affected due to the reheating process of the central column by the combined RF plasma. Accordingly, the exit enthalpy emitted from the DC-RF hybrid torch can be concentrated to the central column of the plasma and controlled by adjusting the DC arc gas flow rate. The swirl in the sheath gas flow turns out to have the opposite effect on the DC arc gas flow rate. The swirling motion of the sheath gas can reduce the back flows near the induction tube wall as well as the axial velocities in the central column of the plasma. Accordingly, the swirl in the sheath gas flow can be used for the functional operation of the DC-RF hybrid plasma along with the DC arc gas flow rate to suppress the back flows at the wall region and to reduce the excessive interactions between the DC arc jet and the ambient RF plasmas. The effects of DC input current on the flow fields of hybrid plasma are similar to those of the DC arc gas flow rate, but the axial velocities for the higher current relatively quickly decay along the centerline. This is in contrast to the increase in the axial velocity remaining in proportion to the increase in the DC arc gas flow rate all the way up to the exit of the DC-RF hybrid plasma. Accordingly, the present integrated numerical analysis suggests that the hybrid plasma field profiles and the entrainment of ambient air from the torch exit are controllable by adjusting the DC arc gas flow rate, the DC input current and swirl in the sheath gas flow taking advantage of

Dilation and Curettage (D&C)

Science.gov (United States)

... For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and Curettage ( ... February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage (D& ...

Estrategias de cuidados de las familias con las personas mayores que viven solas

Directory of Open Access Journals (Sweden)

Julia Gallo Estrada

2013-06-01

Full Text Available Los cambios en el envejecimiento hacen una llamada a trasformar los cuidados dirigidos a las personas mayores que viven solas. Objetivo: Conocer la percepción de la familia sobre el cuidado a los mayores que viven solos. Metodología: Estudio cualitativo mediante análisis de discurso a partir del referencial crítico social y los conceptos de la teoría de Bourdieu. Se realizaron 4 grupos de discusión agrupando a los participantes por género y nivel de instrucción. Resultados: los participantes consideran que la red sociofamiliar puede actuar sobre la discapacidad. Preocupa la manera en la que la persona mayor cubre sus necesidades. Destacan como fundamental el apoyo en la realización de los cuidados. Comparten la idea de que las mujeres mayores se adaptan mejor que los hombres a vivir en soledad. Las mujeres cuidadoras tienden a intervenir precozmente ante los problemas. Los hombres esperan y si pueden delegan. Conclusión: la familia cuestiona los beneficios de la convivencia. La orientación profesional en el cuidado es escasa. Los servicios sociales deben mejorar su accesibilidad.

Effect of D.C. testing water tree deteriorated cable and a preliminary evaluation of V.L.F. as alternate

International Nuclear Information System (INIS)

Eager, G.S. Jr.; Fryszczyn, B.; Katz, C.; ElBadaly, H.A.; Jean, A.R.

1992-01-01

This paper reports that according to the experience of some power utilities, the application of industry recommended high voltage d.c. field tests on 5-35 kV extruded dielectric cables, containing water trees, sometimes causes further deterioration of the insulation. Tests conducted on laboratory aged 15 kV ethylene propylene rubber (EP) and 15 and 28 kV crosslinked polyethylene (XLPE) insulated cables indicate that d.c. proof tests in accordance with AEIC specifications an IEEE test guides without flashover do not appear to cause further deterioration. Depending on the degree of cable aging and the level of test voltage, when flashovers take place, damage may be inflicted to XLPE cables. No damage was observed on aged EP cable, at the same test levels. Because of the aforementioned power utility experience, some users have requested an alternate field proof test. Tests conducted on new XLPE and EP cables indicate that damage to the insulation structure can be detected using VLF (0.1 Hz) voltage at approximately one-third the d.c. voltage level. Field tests conducted on severely tree deteriorated 15 kV polyethylene (PE) cable using AEIC recommended d.c. voltage level of about five times operating voltage level caused cable failure; VLF voltage levels up to two times operating voltage did not. VLF voltage appears to be a suitable alternate to d.c. voltage for field proof testing

Ultrahigh-density trench cpacitors in silicon and their application to integrated DC-DC conversion

NARCIS (Netherlands)

Roozeboom, F.; Bergveld, H.J.; Nowak, K.; Le Cornec, F.; Guiraud, L.; Bunel, C.; Iochem, S.; Ferreira, J.; Ledain, S.; Pieraerts, E.; Pommier, M.

2009-01-01

This paper addresses silicon-based integration of passive components applied to 3D integration with dies of other technologies within one package. Particularly, the development of high-density trench capacitors has enabled the realization of small-formfactor DC-DC converters. As illustration, an

Spectral shaping of a randomized PWM DC-DC converter using maximum entropy probability distributions

CSIR Research Space (South Africa)

Dove, Albert

2017-01-01

Full Text Available maintaining constraints in a DC-DC converter is investigated. A probability distribution whose aim is to ensure maximal harmonic spreading and yet mainaint constraints is presented. The PDFs are determined from a direct application of the method of Maximum...

Programmable dc motor controller

Science.gov (United States)

Hopwood, J. E.

1982-11-01

A portable programmable dc motor controller, with features not available on commercial instruments was developed for controlling fixtures during welding processes. The controller can be used to drive any dc motor having tachometer feedback and motor requirements not exceeding 30 volts, 3 amperes. Among the controller's features are delayed start time, upslope time, speed, and downslope time.

Cirugía bucal mayor ambulatoria

OpenAIRE

Carranza Pelegrina, Daniela; Bellorbí Malet, I.; Brescó Salinas, Vicente Miguel; Berini Aytés, Leonardo; Gay Escoda, Cosme

2004-01-01

La Cirugía Bucal Mayor Ambulatoria ( CBMA) se define como un modelo organizativo óptimo de asis­tencia quirúrgica multidisci­plinaria que permite tratar a determinados pacientes de una forma segura y efectiva sin necesidad de contar con la cama de hospitalización tradicional. De esta manera se llevan a cabo distintos procedimientos diagnósticos y terapéuticos de mediana complejidad en los que el enfermo regresa a su domici­lio después de un periodo de observación y control. Entre las ventajas...

¿Estamos preparados para la atención primaria del adulto mayor?

Directory of Open Access Journals (Sweden)

Marco Zelada R

Full Text Available RESUMEN El Ministerio de Salud ha implementado el Modelo de Atención Integral en Salud enfocado por etapas de vida,siendo parte de este,el Programa de Atención al Adulto Mayor.Con el objetivo de conocer el nivel de conocimientos previos sobre geriatría,se realizó una encuesta a los responsables y miembros del equipo interdisciplinario a cargo de dicho programa.Se entrevistó a 73 profesionales de los cuales el 30%recibió conocimientos en el pregrado,y de éstos, 59%la considero como regular o mala;sólo 10%manifestó que basado en sus conocimientos y experiencia tiene la capacidad para manejar problemas de un adulto mayor.Todos consideraron necesaria la capacitación,para ello prefe- rían talleres teórico-prácticos,con pasantías en servicios de geriatría.Los temas de mayor interés fueron hipertensión arterial (84%,depresión (73%,osteoporosis (66%y diabetes (56%.En conclusión,existe una deficiente formación en geriatría entre los responsables de la atención al adulto mayor,debido a una falta de enseñanza en las universidades y pobre capacitación a los profesionales.

Hybrid Non-Isolated and Non Inverting Nx Interleaved DC-DC Multilevel Boost Converter for Renewable Energy Applications

DEFF Research Database (Denmark)

Bhaskar, Mahajan Sagar; Kulkarni, Rishi M.; Padmanaban, Sanjeevi Kumar

2016-01-01

In this paper hybrid non isolated/ non inverting Nx interleaved DC-DC multilevel Boost Converter for renewable energy applications is presented. The presented hybrid topology is derived from the conventional interleaved converter and the Nx Multilevel boost converter. In renewable energy...... applications, generated energy cannot be directly used at application end. In most of the cases it needs to be stepped up with DC-DC converter at operating voltage levels as per the requirement of the application. Though conventional boost converter can theoretically be used for this purpose, but obtaining...

A comprehensive analysis and hardware implementation of control strategies for high output voltage DC-DC boost power converter

OpenAIRE

Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede; Wheeler, Patrick; Siano, Pierluigi; Hammami, Manel

2017-01-01

Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV) dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned defic...

Resiliencia en trabajadores y en residentes de un centro de personas mayores institucionalizadas

Directory of Open Access Journals (Sweden)

Inmaculada Méndez

2015-04-01

Full Text Available La resiliencia supone un constructo dinámico y multidimensional que alude a la capacidad que tienen las personas para afrontar o recuperarse con éxito de las situaciones adversas. El objetivo del presente estudio ha sido analizar la capacidad de resiliencia en trabajadores y en residentes de un centro de personas mayores institucionalizadas en función de las características sociodemográficas (sexo, edad y estado civil tras la situación adversa por el terremoto ocurrido el Lorca en mayo del 2011. Se ha administrado un cuestionario sociodemográfico desarrollado ad hoc junto a la adaptación de la Escala de Resiliencia de Connor-Davidson (CD-RISC en los sujetos del estudio. Los participantes fueron 20 trabajadores y 34 personas mayores de un centro de personas mayores institucionalizadas de la Región de Murcia (Lorca. La edad media de las personas mayores institucionalizadas fue de 81 años con una desviación típica de 7.68 y la edad media de los cuidadores profesionales fue de 37.85 años y la desviación típica de 9.60. El estudio permite determinar la capacidad de resiliencia atendiendo a características sociodemográficas así como la existencia de diferencias de medias significativas entre la capacidad de tenacidad autoeficacia entre los trabajadores y los residentes del centro de personas mayores lo que permitirá establecer actividades de prevención y/o de intervención.

Direct switching control of DC-DC power electronic converters using hybrid system theory

Energy Technology Data Exchange (ETDEWEB)

Zhao, J.; Lin, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wang, C. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wayne State Univ., Detroit, MI (United States). Div. of Engineering Technology

2010-07-01

A direct switching control (DSC) scheme for power electronics converters was described. The system was designed for use in both traditional and renewable energy applications as well as in electric drive vehicles. The proposed control scheme was based on a detailed hybrid system converter model that used model predictive control (MPC), piecewise affine (PWA) approximations and constrained optimal control methods. A DC-DC converter was modelled as a hybrid machine. Switching among different modes of the DC-DC converter were modelled as discrete events controlled by the hybrid controller. The modelling scheme was applied to a Buck converter. The DSC was used to control the switch of the power converter based on a hybrid machine model. Results of the study showed that the method can be used to regulate output voltage and inductor currents. The method also provides fast transient responses and effectively regulates both currents and voltage. The controller can be used to provide immediate responses to dynamic disturbances and output voltage fluctuations. 23 refs., 7 figs.

Dependencia funcional y bienestar en personas mayores institucionalizadas

Directory of Open Access Journals (Sweden)

María Teresa Rodríguez Díaz

2014-06-01

Full Text Available El presente estudio tiene como objetivo evaluar el bienestar emocional de las personas mayores de 60 años en relación al grado de dependencia funcional. Como indicadores del bienestar se evalúan los niveles de depresión (Yesavage y ansiedad (STAI-R, la satisfacción vital (CSV y la ansiedad ante la muerte (DAS. Se ha realizado un estudio descriptivo transversal en un grupo de personas mayores de 60 años (n=103. Los datos se han recogido usando cuestionarios estandarizados. Para el análisis de los datos se han utilizado correlaciones bivariadas entre las principales medidas, análisis univariado (ANOVA y la prueba de Bonferroni para comprobar las diferencias significativas entre los grupos (p< .05. Los resultados indican que se encuentran diferencias significativas entre los grupos de dependencia para la edad, deterioro cognitivo, depresión y ansiedad ante la muerte. En conclusión, se encuentra una relación directa entre el grado de dependencia funcional y el nivel de malestar emocional.

Informational model verification of ZVS Buck quasi-resonant DC-DC converter

Science.gov (United States)

Vakovsky, Dimiter; Hinov, Nikolay

2016-12-01

The aim of the paper is to create a polymorphic informational model of a ZVS Buck quasi-resonant DC-DC converter for the modeling purposes of the object. For the creation of the model is applied flexible open standards for setting, storing, publishing and exchange of data in distributed information environment. The created model is useful for creation of many and different by type variants with different configuration of the composing elements and different inner model of the examined object.

Envejecimiento poblacional y desigualdades sociales en la mortalidad del adulto mayor en Colombia

Directory of Open Access Journals (Sweden)

Juan Carlos Rivillas

2017-09-01

Full Text Available Objetivo: analizar la magnitud del envejecimiento poblacional y las desigualdades sociales presentes en la mortalidad del adulto mayor en Colombia. Metodología: estudio ecológico usando datos sub-nacionales de mortalidad, pobreza, barreras de acceso a los servicios de salud y analfabetismo, y de la población adulta mayor para analizar brechas. Se calcularon y compararon tendencias de tres indicadores de impacto: la esperanza de vida (2005-2020, los Índices de envejecimiento y sobre-envejecimiento (2005-2012. Se estimaron tres medidas para resumir la desigualdad absoluta y relativa: el Índice de Desigualdad de la Pendiente (IDP, el Índice Relativo de Desigualdad (IRD de Kunst y Mackenbach, y el Índice de Concentración (IC. Resultados: la proporción de personas mayores será cada vez mayor en Colombia. Las barreras de acceso a los servicios de salud fue la dimensión más inequitativa. Dos patrones de desigualdad fueron identificados: una exclusión marginal en el 60% de los adultos mayores con más ventajas y oportunidades, y un patrón de gradiente lineal presente solo en la incidencia de pobreza. El quintil 3 fue el grupo de departamentos más afectado por la inequidad a lo largo de las dimensiones evaluadas. Discusión: este estudio aporta evidencia sobre patrones de desigualdad en la mortalidad del adulto mayor. A nivel de tendencias, solo fue posible conocer que la brecha ha empeorado en incidencia de pobreza. Conclusiones: las recomendaciones se centran en cinco áreas de acción, para lograr un contexto deseable para el abordaje del envejecimiento poblacional y la reducción de las desigualdades, como desafíos del sistema de salud y de protección social, y que pueden socavar la realización progresiva de la cobertura universal en salud y el logro de los objetivos de desarrollo sostenible para 2030.

Switched capacitor DC-DC converter with switch conductance modulation and Pesudo-fixed frequency control

DEFF Research Database (Denmark)

Larsen, Dennis Øland; Vinter, Martin; Jørgensen, Ivan Harald Holger

A switched capacitor dc-dc converter with frequency-planned control is presented. By splitting the output stage switches in eight segments the output voltage can be regulated with a combination of switching frequency and switch conductance. This allows for switching at predetermined frequencies, 31...

A Novel Dual-input Isolated Current-Fed DC-DC Converter for Renewable Energy System

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2010-01-01

In this paper, a novel isolated current-fed DC-DC converter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy...

Experience from design, prototyping and production of a DC-DC conversion powering scheme for the CMS Phase-1 Pixel Upgrade

International Nuclear Information System (INIS)

Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Preuten, M.; Rauch, M.; Schmitz, S.; Wlochal, M.

2016-01-01

The CMS collaboration has adopted a DC-DC conversion powering scheme for the Phase-1 Upgrade of its pixel detector. DC-DC buck converters with a conversion ratio of around 3 are installed on the support structures, outside of the sensitive tracking region, requiring a re-design of the low and high voltage distribution to the pixel modules. After several years of R and D, the project has entered the production phase. A total of 1800 DC-DC converters are being produced, and rigorous quality assurance and control is being employed during the production process. The testing program is outlined, results from mass production are presented and issues that have been encountered are described. In addition, two system level challenges, namely the choice of output voltage in the presence of large, load-dependent voltage drops, and the thermal management required to remove the heat load caused by the DC-DC converters, are discussed

Analytical Comparison of Dual-Input Isolated dc-dc Converter with an ac or dc Inductor for Renewable Energy Systems

DEFF Research Database (Denmark)

Zhang, Zhe; Mira Albert, Maria del Carmen; Andersen, Michael A. E.

2017-01-01

This paper presents two configurations of dualinput (DI) or three-port (TPC) isolated dc-dc converters for hybrid renewable energy systems such as photovoltaics and batteries. These two converters are derived by integrating an interleaved boost converter and a single-active bridge converter...... and control perspective, distinct in operation principles, voltage/power transfer functions, loss distributions, soft-switching constraints, and power efficiency under the same operating conditions. Moreover, the inductor design differs greatly between these two cases. In this paper, a comprehensive...

Analysis of a high power, resonant DC-DC converter for DC wind turbines

DEFF Research Database (Denmark)

Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

2018-01-01

This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high-voltage DC wind turbines. Compared to a frequency controlled series resonant converter operated in sub resonant mode, the method (entitled pulse removal technique) allows...

High-Efficiency Photovoltaic System Using Partially-Connected DC-DC Converter

Science.gov (United States)

Uno, Masatoshi; Kukita, Akio; Tanaka, Koji

Power conversion electronics for photovoltaic (PV) systems are desired to operate as efficiently as possible to exploit the power generated by PV modules. This paper proposes a novel PV system in which a dc-dc converter is partially connected to series-connected PV modules. The proposed system achieves high power-conversion efficiency by reducing the passing power and input/output voltages of the converter. The theoretical operating principle was experimentally validated. Resultant efficiency performances of the proposed and conventional systems demonstrated that the proposed system was more efficient in terms of power conversion though the identical converter was used for the both systems.

Very High Frequency Resonant DC/DC Converters for LED Lighting

DEFF Research Database (Denmark)

Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

2013-01-01

This paper presents a very high frequency DC/DC converter for LED lighting. Several resonant topologies are compared and their usability discussed. At the end the resonant SEPIC converter is chosen based on the achievable power density and total bill of material. Simulations of a 51 MHz converter...... with 40 V input and 15 V output are made. The simulation shows possibility of achieving efficiency up to 87 % even with a HEXFET Power MOSFET. Three prototypes of the simulated converter are implemented showing good correlation with simulations. The prototypes have efficiencies up to 84 % and power...

A THREE-PHASE BOOST DC-AC CONVERTER

African Journals Online (AJOL)

dc-ac converter (inverter) based on the dc-dc boost converters. ... Sliding mode controllers are designed to perform a robust control for the ... Computer simulations and spectral analysis demon- ... the conventional three-phase buck inverter,.

Linking DC together with TRSL

DEFF Research Database (Denmark)

Haxthausen, Anne; Yong, Xia

1999-01-01

In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form of constra......In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form.......TRSL is a real-time extension of the RAISE Specification Language (RSL) [Rlg92] which together with its associated method [Rmg95]and tools has shown to be very useful in the industrial development of software systems. Therefore, a promising approach for the development of real-time systemscould be to use DC...... for high-level specifications of real-time requirementsand TRSL for specifying real-time implementations in the form of timed communicating concurrent processes.In order to link DC and TRSL together in a well-founded way, we formally define what it means for a TRSL process to satisfy a DC requirement...

A Four-Phase High Voltage Conversion Ratio Bidirectional DC-DC Converter for Battery Applications

Directory of Open Access Journals (Sweden)

Li-Kun Xue

2015-06-01

Full Text Available This study presents a four-phase interleaved high voltage conversion ratio bidirectional DC-DC converter circuit based on coupled inductors and switched capacitors, which can eliminate the defects of conventional high voltage conversion ratio bidirectional DC-DC converters in terms of high-voltage/current stress, less efficiency and low-power limitation. Parallel channels are used to reduce current stress at the low-voltage side and series connected switched capacitors are used to enlarge voltage conversion ratio, reduce voltage stress and achieve auto current sharing. This paper proposes the operation principle, feature analysis and optimization design considerations. On this basis the objectives of high voltage conversion ratio, low voltage/current stress, high power density, high efficiency and high-power applications can be achieved. Some experimental results based on a 500 W prototype converter (24 V to 48 V at low-voltage side, 400 V at high-voltage side are given to verify the theoretical analysis and the effectiveness of the proposed converter.

Model Based Optimization of Integrated Low Voltage DC-DC Converter for Energy Harvesting Applications

Science.gov (United States)

Jayaweera, H. M. P. C.; Muhtaroğlu, Ali

2016-11-01

A novel model based methodology is presented to determine optimal device parameters for the fully integrated ultra low voltage DC-DC converter for energy harvesting applications. The proposed model feasibly contributes to determine the maximum efficient number of charge pump stages to fulfill the voltage requirement of the energy harvester application. The proposed DC-DC converter based power consumption model enables the analytical derivation of the charge pump efficiency when utilized simultaneously with the known LC tank oscillator behavior under resonant conditions, and voltage step up characteristics of the cross-coupled charge pump topology. The verification of the model has been done using a circuit simulator. The optimized system through the established model achieves more than 40% maximum efficiency yielding 0.45 V output with single stage, 0.75 V output with two stages, and 0.9 V with three stages for 2.5 kΩ, 3.5 kΩ and 5 kΩ loads respectively using 0.2 V input.

State trajectories used to observe and control dc-to-dc converters

Science.gov (United States)

Burns, W. W., III; Wilson, T. G.

1976-01-01

State-plane analysis techniques are employed to study the voltage stepup energy-storage dc-to-dc converter. Within this framework, an example converter operating under the influence of a constant on-time and a constant frequency controller is examined. Qualitative insight gained through this approach is used to develop a conceptual free-running control law for the voltage stepup converter which can achieve steady-state operation in one on/off cycle of control. Digital computer simulation data are presented to illustrate and verify the theoretical discussions presented.

Tecnología asistencial móvil, con realidad aumentada, para las personas mayores

Directory of Open Access Journals (Sweden)

Rafael Saracchini

2015-07-01

Full Text Available Las posibilidades que ofrecen las tecnologías son muchas, sin embargo, las personas mayores son a menudo incapaces de disfrutar de ellas plenamente, sintiéndose desanimadas o intimidadas por estos nuevos dispositivos. Esto les lleva a un progresivo aislamiento en una sociedad donde es esencial conocer las distintas formas de comunicación a través de Internet y las TIC. En este trabajo presentamos un estudio realizado durante el proyecto Nacodeal, cuyo objetivo es ofrecer una solución tecnológica para proporcionar autonomía y una mejor calidad de vida para las personas mayores durante sus actividades diarias mediante la integración de las TIC. Para lograr este objetivo se ha desarrollado tecnología puntera en realidad aumentada (RA, así como servicios de Internet e interfaces para dispositivos móviles especialmente diseñados para personas mayores. Estas tecnologías emplean la infraestructura presente en la mayoría de casas y centros de cuidados de mayores. Presentamos un prototipo de sistema compuesto por una tableta y un dispositivo de RA portátil, así como el análisis del impacto social en la interacción con usuarios y la valoración de la aceptación y usabilidad. Esta evaluación se llevó a cabo a través de grupos focales y pruebas piloto individuales con 48 participantes: ancianos, cuidadores y expertos. Sus comentarios concluyen que existen fuertes beneficios e intereses por parte de las personas mayores en las TIC asistenciales basadas en RA, especialmente en los aspectos relacionados con la comunicación y autonomía.

Design of an Input-Parallel Output-Parallel LLC Resonant DC-DC Converter System for DC Microgrids

Science.gov (United States)

Juan, Y. L.; Chen, T. R.; Chang, H. M.; Wei, S. E.

2017-11-01

Compared with the centralized power system, the distributed modularized power system is composed of several power modules with lower power capacity to provide a totally enough power capacity for the load demand. Therefore, the current stress of the power components in each module can then be reduced, and the flexibility of system setup is also enhanced. However, the parallel-connected power modules in the conventional system are usually controlled to equally share the power flow which would result in lower efficiency in low loading condition. In this study, a modular power conversion system for DC micro grid is developed with 48 V dc low voltage input and 380 V dc high voltage output. However, in the developed system control strategy, the numbers of power modules enabled to share the power flow is decided according to the output power at lower load demand. Finally, three 350 W power modules are constructed and parallel-connected to setup a modular power conversion system. From the experimental results, compared with the conventional system, the efficiency of the developed power system in the light loading condition is greatly improved. The modularized design of the power system can also decrease the power loss ratio to the system capacity.

Considerations of Physical Design and Implementation for 5 MHz-100 W LLC Resonant DC-DC Converters

Directory of Open Access Journals (Sweden)

Akinori Hariya

2016-01-01

Full Text Available Recently, high power-density, high power-efficiency, and wide regulation range isolated DC-DC converters have been required. This paper presents considerations of physical design and implementation for wide regulation range MHz-level LLC resonant DC-DC converters. The circuit parameters are designed with 3–5 MHz-level switching frequency. Also, the physical parameters and the size of the planar transformer are optimized by using derived equations and finite element method (FEM with Maxwell 3D. Some experiments are done with prototype LLC resonant DC-DC converter using gallium nitride high electron mobility transistors (GaN-HEMTs; the input voltage is 42–53 V, the reference output voltage is 12 V, the load current is 8 A, the maximum switching frequency is about 5 MHz, the total volume of the circuit is 4.1 cm3, and the power density of the prototype converter is 24.4 W/cc.

Design and implementation of current fed DC-DC converter for PHEV application using renewable source

Science.gov (United States)

Milind Metha, Manish; Tutki, Sanjay; Rajan, Aju; Elangovan, D.; Arunkumar, G.

2017-11-01

As the fossil fuels are depleting day by day, the use of renewable energy sources came into existence and they evolved a lot lately. To increase efficiency and productivity in the hybrid vehicles, the existence less efficient petroleum and diesel IC engines need to be replaced with the new and efficient converters with renewable energy sources. This has to be done in such a way that impacts three factors mainly: cost, efficiency and reliability. The PHEVs that have been launched and the upcoming PHEVs using converters with voltage range around 380V to 400V generated with power ranges between 2.4KW to 2.8KW. The basic motto of this paper is to design a prolific converter while considering the factor such as cost and size. In this paper, a two stage DC-DC converter is proposed and the proposed DC-DC converter is utilized to endeavour voltage from 24V (photovoltaic source) to a yield voltage of 400V and to meet the power demand of 250W, since only one panel is being used for this proposed paper. This paper discuss in detail about why and how the current fed DC-DC converter is utilized along with a voltage doubler, thus reducing transformer turns and thereby reducing overall size of the product. Simulation and hardware results have been presented along with calculations for duty cycle required for firing sequence for different values of transformer turns.

The effects of intermittent, CD4-guided antiretroviral therapy on body composition and metabolic parameters

NARCIS (Netherlands)

Martinez, Esteban; Visnegarwala, Fehmida; Grund, Birgit; Thomas, Avis; Gibert, Cynthia; Shlay, Judith; Drummond, Fraser; Pearce, Daniel; Edwards, Simon; Reiss, Peter; El-Sadr, Wafaa; Carr, Andrew

2010-01-01

Objective: To assess the effects of decreased antiretroviral therapy exposure on body fat and metabolic parameters. Design: Substudy of the Strategies for Management of Anti-Retroviral Therapy study, in which participants were randomized to intermittent CD4-guided [Drug Conservation (DC) group] or

Series-Connected High Frequency Converters in a DC Microgrid System for DC Light Rail Transit

Directory of Open Access Journals (Sweden)

Bor-Ren Lin

2018-01-01

Full Text Available This paper studies and presents a series-connected high frequency DC/DC converter connected to a DC microgrid system to provide auxiliary power for lighting, control and communication in a DC light rail vehicle. Three converters with low voltage and current stresses of power devices are series-connected with single transformers to convert a high voltage input to a low voltage output for a DC light rail vehicle. Thus, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs with a low voltage rating and a turn-on resistance are adopted in the proposed circuit topology in order to decrease power losses on power switches and copper losses on transformer windings. A duty cycle control with an asymmetric pulse-width modulation is adopted to control the output voltage at the desired voltage level. It is also adopted to reduce switching losses on MOSFETs due to the resonant behavior from a leakage inductor of an isolated transformer and output capacitor of MOSFETs at the turn-on instant. The feasibility and effectiveness of the proposed circuit have been verified by a laboratory prototype with a 760 V input and a 24 V/60 A output.

Guest Editorial Special Issue on Structured DC Microgrids

DEFF Research Database (Denmark)

Guerrero, Josep M.; Tan, Don F. D.

2017-01-01

With the development of dc coupled devices, such as photovoltaic generations, batteries, supercapacitors, LEDs, computers, and electronics equipment, low-voltage dc distribution networks, structured dc microgrids are emerging as a natural platform to integrate renewable energy sources. However...... in either series/parallel, forming a number of dc busses with different voltage levels. Recently, with the advance of new dc power technologies, several ongoing standards, alliances, and initiatives are bringing the possibility of developing future homes, offices, buildings, campuses, datacenters, ships......, satellites, aircrafts, and other electrical power systems to operate totally or dominantly in dc. Research is being carried out in both the system and component levels of modeling, control, and stability of structured dc microgrids. New high-efficiency topologies and protections are also key nontrivial...

Mayores e Internet: La Red como fuente de oportunidades para un envejecimiento activo

Directory of Open Access Journals (Sweden)

Carmen Llorente Barroso

2015-07-01

Full Text Available El progresivo envejecimiento de las sociedades ha llevado a los organismos internacionales y europeos a desarrollar programas de envejecimiento activo, capaces de construir una nueva cultura sobre el papel de las personas mayores en la sociedad. Estos incluyen aspectos sociales de carácter comunicacional que, sin embargo, han tenido menos desarrollo investigador que otros más apremiantes, vinculados a aspectos físicos y económicos. Esta investigación atiende precisamente a estas variables comunicacionales, abordando la vinculación de los mayores con Internet y planteándose dos objetivos principales: Conocer las utilidades que tiene Internet para este colectivo y explicar los motivos que convertirían a este medio en una fuente de oportunidades para un envejecimiento activo. Para satisfacerlos, se utiliza una metodología cualitativa que se apoya en el desarrollo de tres grupos de discusión constituidos por entre cinco y seis personas de 56 a 81 años y moderados por un experto. Los resultados obtenidos del análisis cualitativo del contenido en cada discusión indican que Internet es una fuente de oportunidades para los mayores, que pueden aglutinarse en cuatro categorías: informativas, comunicativas, transaccionales y administrativas, y de ocio y entretenimiento. Estas oportunidades optimizan la calidad de vida de los mayores y contribuyen a su envejecimiento activo, si bien, su máximo aprovechamiento precisa de programas de «e-Inclusion» y metodologías que aproximen Internet a los mayores, facilitándoles una formación en competencias digitales.

A new soft-switched high step-up DC-DC converter with dual coupled inductors

DEFF Research Database (Denmark)

Forouzesh, Mojtaba; Shen, Yanfeng; Yari, Keyvan

2017-01-01

This paper introduces a new efficient high step-up dc-dc converter with a shared input path and dual series coupled inductors at the output. This converter is suitable for high power applications due to its shared input current that puts low current stresses on the low voltage side switches...

75 FR 80744 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-81 (MD-81), DC-9-82 (MD-82...

Science.gov (United States)

2010-12-23

...-1203; Directorate Identifier 2010-NM-168-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas... amends Sec. 39.13 by adding the following new airworthiness directive (AD): McDonnell Douglas Corporation... Douglas Corporation Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87) and MD-88...

Design and implementation of a bidirectional current-controlled voltage-regulated DC-DC switched-mode converter

CSIR Research Space (South Africa)

Coetzer, A

2016-01-01

Full Text Available The design and implementation of a bidirectional current-controlled voltage-regulated DC-DC converter is presented. The converter is required to connect a battery of electrochemical cells (the battery) to an asynchronous motor-drive unit via a...

A high voltage gain quasi Z-source isolated DC/DC converter

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Blaabjerg, Frede; Loh, Poh Chiang

2014-01-01

A compact quasi-Z-source DC/DC converter is presented with high voltage gain, isolated output, and improved efficiency. The improvements in size and performance were achieved by using a square wave inverter with only two output switches driving an isolating transformer in push-pull mode, followed...... by a voltage doubling output rectifier. The converter is well-suited to applications requiring a high voltage gain, especially renewable energy sources such as photovoltaic and fuel-cell power supplies. To demonstrate the converter's performance a prototype designed to output 400 V at 500 W was constructed...

Four Quadrants Integrated Transformers for Dual-input Isolated DC-DC Converters

DEFF Research Database (Denmark)

Ouyang, Ziwei; Zhang, Zhe; Andersen, Michael A. E.

2012-01-01

A common limitation of power coupling effect in some known multiple-input dc-dc converters has been addressed in many literatures. In order to overcome this limitation, a new concept for decoupling the primary windings in the integrated multiple-winding transformers based on 3-dimensional (3D...... perpendicular primary windings, a name of “four quadrants integrated transformers” (FQIT) is therefore given to the proposed construction. Since the two primary windings are uncoupled, the FQIT allows the two input power stages to transfer the energy into the output load simultaneously or at any...

A green roof grant program for Washington DC

International Nuclear Information System (INIS)

Johnson, P.A.

2007-01-01

The Chesapeake Bay Foundation (CBF) began its green roof demonstration project with $300,000 in funding provided by the DC Water and Sewer Authority. This paper reviewed the history of the project, its goals and early findings. The main objective was to demonstrate the technical, policy and economic feasibility of installing green roofs on commercial buildings in Washington DC and to promote green roofs as a means to manage storm water and improve water quality through the reduction of excessive runoff. The CBF has issued grants for the installation of 7 green roofs varying in size, design, location, and use. The projects included both new and existing structures designed to improve storm-water management in an urban area with significant pollution stress on the adjacent rivers. This paper provided technical, cost, and performance evaluations of each roof. A public outreach segment provided information to decision-makers to encourage more widespread replication of green roof technology throughout the metropolitan area. Much of the District of Columbia is served by a combined sewer system that becomes overloaded and discharges raw sewage into adjacent rivers during even moderately heavy rains. An average of 75 overflow events each year result in 1.5 billion gallons discharged into the Anacostia River. The installation of green roofs on buildings in the combined sewer area would retain storm water during these heavy rains and reduce the amount of overflow discharges. Apartments, as well as commercial and government buildings with mostly flat roofs are the most likely candidates for green roofs. The demonstration roofs are intended to become models, which all building owners could use as a guide for future plans for construction or re-construction to expand green roof coverage in Washington DC. It was emphasized that although such large-scale replication will take time and financial investments, it is achievable given enough political will and commercial awareness of

Factores asociados al maltrato del adulto mayor de Antioquia, 2012

Directory of Open Access Journals (Sweden)

Sara M. Cano

2015-07-01

Full Text Available Objetivo: determinar los factores asociados al maltrato del adulto mayor del departamento de Antioquia en el año 2012. Metodología: mediante estudio descriptivo transversal, se caracterizaron los factores demográficos, económicos y de salud mental de la población adulta mayor de Antioquia para el año 2012, con el fin de aportar al análisis de la situación de salud y condiciones de vida del adulto mayor. El estudio se basó en los resultados del instrumento aplicado por la Universidad ces a 4.215 adultos de sesenta años y más de edad, en el cual se indagó sobre percepción de maltrato, funcionamiento cognitivo, nivel de depresión, nivel de ansiedad, apoyo social, escala de recursos sociales, entre otras; los resultados se expandieron a 654.473 adultos del departamento. Resultados: el 72,8% de adultos del departamento son mujeres, 53,7% vive en Medellín, 55% tiene primaria incompleta, 72,9% pertenece a estratos socioeconómicos 1 y 2, 45,1% no registraron ingresos en el último mes, 26,3% tiene riesgo de depresión y 34,4% tiene riesgo de ansiedad, 2,5% reportó haber sufrido descuido, 5,0% necesidades afectivas ignoradas, 1,7% algún caso de agresión física, 0,4% agresión sexual y 1,3%, afirmó haber sufrido maltrato económico. Las variables estrato socioeconómico, tipo de vivienda, etnia, riesgo de depresión, riesgo de ansiedad, riesgo de deterioro cognitivo y red de apoyo fueron las que más ayudaron a explicar la presencia de maltrato. Conclusión: enfrentar este problema requiere de una atención integral a las necesidades de los adultos mayores, participación de todos los sectores de la sociedad y conciencia transgeneracional.

Metabolismo posprandial en adultos mayores normales de nivel del mar

Directory of Open Access Journals (Sweden)

Fausto Garmendia

2003-06-01

Full Text Available Objetivo: Determinar las modificaciones normales del metabolismo después de la ingestión de alimentos. Material y Métodos: Se ha estudiado a 33 personas de ambos géneros, adultos mayores, de nivel del mar, tanto en ayunas como después de la ingesta de una mezcla alimenticia consistente en 730 kcal, con 55,4% de grasas, 37,2% de hidratos de carbono y 7,4% de proteínas. Se ha medido el perfil metabólico en ayunas y luego de la ingesta alimentaria, la glucosa, triglicérido (Tg, ácidos grasos no esterificados (AGNE, insulina por métodos convencionales hasta la 6a hora; se ha calculado las concentraciones de colesterol LDL y VLDL utilizando la fórmula de Friedewald; el colesterol no-HDL, mediante la sustracción del valor del colesterol HDL al valor de colesterol total (CT. Resultados: La glicemia se elevó discretamente, regresando a valores basales a la 2a hora; la insulinemia se incrementó durante 4 horas; los triglicéridos comenzaron a elevarse en sangre a partir de la 2a hora y llegaron al máximo a la 4a hora, para luego iniciar el descenso no completo en la 6a hora. Los AGNE disminuyeron a partir de los 30 minutos, llegando al máximo de caída a las 2 horas; luego se apreció un rebote máximo a la 6a hora, inclusive mayor al valor basal. Conclusiones: Estos resultados demuestran que no es suficiente obtener información del metabolismo intermediario en ayunas, sino que el estudio posprandial permite mayor información. Es la primera vez en nuestro país que se obtiene información sobre el metabolismo intermediario en fase posprandial en una muestra de la población normal que se encuentra en una edad de mayor riesgo cardiovascular.

High Current Planar Transformer for Very High Efficiency Isolated Boost DC-DC Converters

DEFF Research Database (Denmark)

Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

2014-01-01

This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac-resistance a......This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac......-resistance and transformer leakage inductance. Design and optimization procedures are validated based on an experimental prototype of a 6 kW dcdc isolated full bridge boost converter developed on fully planar magnetics. The prototype is rated at 30-80 V 0-80 A on the low voltage side and 700-800 V on the high voltage side...... with a peak efficiency of 97.8% at 80 V 3.5 kW. Results highlights that thick copper windings can provide good performance at low switching frequencies due to the high transformer filling factor. PCB windings can also provide very high efficiency if stacked in parallel utilizing the transformer winding window...

Diabetes Mellitus en el adulto mayor

OpenAIRE

Guerrero-Godínez, Juan; Barragán-Vigil, Ana; Navarro-Macias, Carmen; Murillo-Bonilla, Luis; Uribe-González, Paul; Sánchez-Cruz, Martha

2017-01-01

La Diabetes Mellitus, una enfermedad crónica que afecta a todo el mundo siendo nuestro país México, el primer lugar con esta enfermedad, su incidencia aumenta junto con la edad hasta un 20% en personas mayores de 60 años todos ellos susceptibles a síndromes geriátricos, con posibles repercusiones ya sea por falta de control de niveles de glicemia o por un exceso en el control. El objetivo de esta revisión no sistemática es concientizar a la población general de la diabetes mellitus y el conte...

El estado de salud del adulto mayor en América Latina

OpenAIRE

R. Todd Jewell; Máximo Rossi; Patricia Triunfo

2006-01-01

Haciendo uso de los datos de la Encuesta sobre Salud, Bienestar y Envejecimiento, este trabajo analiza el estado de salud de las personas mayores a 60 años en cinco países de América Latina: Argentina, Brasil, Chile, México y Uruguay. Empleando modelos probit ordenados fue posible investigar los efectos de variables socioeconómicas sobre el estado de salud auto-reportado. Los resultados indican que la autopercepción de la salud está relacionada positivamente con una buena nutrición, una mayor...

Factores asociados al riesgo nutricional del adulto mayor no institucionalizado, Pasto, Colombia

OpenAIRE

Hernández Rangel, Juanita del Pilar

2017-01-01

Objetivo: determinar los factores sociales, demográficos, y de salud que se asocian al riesgo nutricional de los adultos mayores no institucionalizados de la ciudad de Pasto en el año 2016. Metodología: estudio de prevalencia analítico a partir del análisis secundario de los datos para la ciudad de Pasto de la encuesta “Índice de vulnerabilidad de los adultos mayores, en tres ciudades de Colombia, 2016”. Se utilizó la Iniciativa del Tamizaje Nutricional (NSI) con la escala DETERMINE para l...

Prevalencia y factores de riesgo en personas adultas mayores en Costa Rica

OpenAIRE

Barrientos Calvo, Isabel; Madrigal Leer, Fabián; Abarca Gómez, Leandra

2014-01-01

El riesgo nutricional es la potencialidad de desarrollar desnutrición por déficit de alimentación, debido a diversos factores. La prevalencia del riesgo nutricional en adultos mayores utilizando la Valoración Nutricional Mínima (MNA®) en Europa y Estados Unidos es de un 15 % y 20 %. El estudio SABE-México, determinó un 31,8 %. Objetivo: Conocer la prevalencia de riesgo nutricional y sus principales factores asociados en los adultos mayores que asisten a un primer nivel de atención en Costa Ri...

Estrategias orientadoras apara la elaboración de proyectos de adultos mayores

OpenAIRE

Ciano, Natalia

2011-01-01

En este trabajo se presenta el proyecto de investigación "estrategias orientadoras para la elaboración de proyectos en adultos mayores" que se propone aplicar las estrategias orientadoras diseñadas en un proyecto anterior a los efectos de analizar el impacto de las mismas en la elaboración de proyectos de adultos mayores. Articula el Modelo de Envejecimiento Activo y el Modelo Teórico Operativo en Orientación. Se parte de los principales resultados obtenidos en la investigación anterior, los ...

Competencias socio-emocionales en adultos mayores de la ciudad de Buenos Aires

OpenAIRE

Mikulic, Isabel M.; Caballero, Romina; Aruanno, Yanina

2014-01-01

Con el aumento de la población de adultos mayores, se plantean importantes retos a nivel internacional. Los estudios se focalizaron en factores demográficos, cognitivos y físicos, en cambio, los emocionales fueron escasamente investigados en esta etapa vital. El objetivo de este estudio es evaluar el patrón de competencias socioemocionales en 53 adultos mayores (M =69; DE =4.2), de ambos sexos, y comparar sus diferencias con 53 jóvenes adultos. A todos los participantes se les administró el I...

DC Voltage Control and Power-Sharing of Multi-Terminal DC Grids Based on Optimal DC Power Flow and Flexible Voltage Droop Strategy

Directory of Open Access Journals (Sweden)

F. Azma

2015-06-01

Full Text Available This paper develops an effective control framework for DC voltage control and power-sharing of multi-terminal DC (MTDC grids based on an optimal power flow (OPF procedure and the voltage-droop control. In the proposed approach, an OPF algorithm is executed at the secondary level to find optimal reference of DC voltages and active powers of all voltage-regulating converters. Then, the voltage droop characteristics of voltage-regulating converters, at the primary level, are tuned based on the OPF results such that the operating point of the MTDC grid lies on the voltage droop characteristics. Consequently, the optimally-tuned voltage droop controller leads to the optimal operation of the MTDC grid. In case of variation in load or generation of the grid, a new stable operating point is achieved based on the voltage droop characteristics. By execution of a new OPF, the voltage droop characteristics are re-tuned for optimal operation of the MTDC grid after the occurrence of the load or generation variations. The results of simulation on a grid inspired by CIGRE B4 DC grid test system demonstrate efficient grid performance under the proposed control strategy.

Linking DC together with TRSL

DEFF Research Database (Denmark)

Haxthausen, Anne Elisabeth; Yong, X.

2000-01-01

in a method for real-time developments. An operational semantics with behavior is specified for TRSL. It is defined what its means for a TRSL process to satisfy a DC requirement, and a method for verifying whether the satisfaction relation holds or not is provided. Our contribution also demonstrates a general......Duration Calculus (DC) is an interval-based real-time logic, which can be used in capturing and eliciting users' real-time requirements. The Timed RAISE Specification Language (TRSL) is an extension of the RAISE Specification Language with real-time features. This paper links DC and TRSL together...

All Digital Switch-Mode DC/DC Converters with BIST Functionality for Harsh Space Environments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The Space Micro Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

Open-circuit fault detection and tolerant operation for a parallel-connected SAB DC-DC converter

DEFF Research Database (Denmark)

Park, Kiwoo; Chen, Zhe

2014-01-01

This paper presents an open-circuit fault detection method and its tolerant control strategy for a Parallel-Connected Single Active Bridge (PCSAB) dc-dc converter. The structural and operational characteristics of the PCSAB converter lead to several advantages especially for high power applicatio...

Hierarchical Power Sharing Control in DC Microgrids

DEFF Research Database (Denmark)

Peyghami, Saeed; Mokhtari, Hossein; Blaabjerg, Frede

2016-01-01

Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [18], space applications [10], aircraft [12], offshore wind farms, electric vehicles [56], DC home systems [5, 20], and high-voltage DC transmission systems...

75 FR 38017 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-10 Series Airplanes, DC-9-30...

Science.gov (United States)

2010-07-01

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-10 Series Airplanes, DC-9-30 Series... previously to all known U.S. owners and operators of the McDonnell Douglas Corporation airplanes identified... INFORMATION: On July 15, 2009, we issued AD 2009-15-16, which applies to all McDonnell Douglas Model DC-9-10...

Experimental study of dynamic behaviors and routes to chaos in DC-DC boost converters

International Nuclear Information System (INIS)

Cafagna, D.; Grassi, G.

2005-01-01

This paper illustrates an experimental study of a current-programmed DC-DC boost converter, with the aim of investigating possible pathways through which the converter may enter chaos. In particular, based on experimental measurements, it is shown that variations of input voltage and reference current can generate periodic, subharmonic, quasi-periodic and chaotic behaviors

Halbach array DC motor/generator

Science.gov (United States)

Merritt, B.T.; Dreifuerst, G.R.; Post, R.F.

1998-01-06

A new configuration of DC motor/generator is based on a Halbach array of permanent magnets. This motor does not use ferrous materials so that the only losses are winding losses and losses due to bearings and windage. An ``inside-out`` design is used as compared to a conventional motor/generator design. The rotating portion, i.e., the rotor, is on the outside of the machine. The stationary portion, i.e., the stator, is formed by the inside of the machine. The rotor contains an array of permanent magnets that provide a uniform field. The windings of the motor are placed in or on the stator. The stator windings are then ``switched`` or ``commutated`` to provide a DC motor/generator much the same as in a conventional DC motor. The commutation can be performed by mechanical means using brushes or by electronic means using switching circuits. The invention is useful in electric vehicles and adjustable speed DC drives. 17 figs.

Halbach array DC motor/generator

Science.gov (United States)

Merritt, Bernard T.; Dreifuerst, Gary R.; Post, Richard F.

1998-01-01

A new configuration of DC motor/generator is based on a Halbach array of permanent magnets. This motor does not use ferrous materials so that the only losses are winding losses and losses due to bearings and windage. An "inside-out" design is used as compared to a conventional motor/generator design. The rotating portion, i.e., the rotor, is on the outside of the machine. The stationary portion, i.e., the stator, is formed by the inside of the machine. The rotor contains an array of permanent magnets that provide a uniform field. The windings of the motor are placed in or on the stator. The stator windings are then "switched" or "commutated" to provide a DC motor/generator much the same as in a conventional DC motor. The commutation can be performed by mechanical means using brushes or by electronic means using switching circuits. The invention is useful in electric vehicles and adjustable speed DC drives.

Bifurcation Analysis of a DC-DC Bidirectional Power Converter Operating with Constant Power Loads

Science.gov (United States)

Cristiano, Rony; Pagano, Daniel J.; Benadero, Luis; Ponce, Enrique

Direct current (DC) microgrids (MGs) are an emergent option to satisfy new demands for power quality and integration of renewable resources in electrical distribution systems. This work addresses the large-signal stability analysis of a DC-DC bidirectional converter (DBC) connected to a storage device in an islanding MG. This converter is responsible for controlling the balance of power (load demand and generation) under constant power loads (CPLs). In order to control the DC bus voltage through a DBC, we propose a robust sliding mode control (SMC) based on a washout filter. Dynamical systems techniques are exploited to assess the quality of this switching control strategy. In this sense, a bifurcation analysis is performed to study the nonlinear stability of a reduced model of this system. The appearance of different bifurcations when load parameters and control gains are changed is studied in detail. In the specific case of Teixeira Singularity (TS) bifurcation, some experimental results are provided, confirming the mathematical predictions. Both a deeper insight in the dynamic behavior of the controlled system and valuable design criteria are obtained.

Red social y salud del adulto mayor en perspectiva comparada: Costa Rica, España e Inglaterra

Directory of Open Access Journals (Sweden)

Castro, Teresa

2007-07-01

Full Text Available En el presente trabajo se explora la relación entre la red social más próxima al adulto mayor, los vínculos establecidos con otros miembros del hogar y con los hijos, y las condiciones de salud en la vejez, desde una perspectiva internacional comparada. Para ello se cuenta con evidencias empíricas de una sociedad latinoamericana (costarricense, una sociedad latino-europea (española y una sociedad anglosajona (británica. Los adultos mayores de los tres países analizados han mostrado modelos de redes familiares claramente diferenciados, caracterizados por la corresidencia intergeneracional (caso latinoamericano, por la independencia (caso anglosajón y por la independencia (sólo residencial (caso latino-europeo. La convivencia entre miembros de la misma familia parece tener efectos positivos cuando no es por necesidad. La frecuencia de los contactos con otros miembros de la familia muestra un mayor efecto positivo cuanto mayor es la independencia de los adultos mayores.

Red social y salud del adulto mayor en perspectiva comparada: Costa Rica, España e Inglaterra

Directory of Open Access Journals (Sweden)

Dolores Puga

2007-01-01

Full Text Available En el presente trabajo se explora la relación entre la red social más próxima al adulto mayor, los vínculos establecidos con otros miembros del hogar y con los hijos, y las condiciones de salud en la vejez, desde una perspectiva internacional comparada. Para ello se cuenta con evidencias empíricas de una sociedad latinoamericana (costarricense, una sociedad latino-europea (española y una sociedad anglosajona (británica. Los adultos mayores de los tres países analizados han mostrado modelos de redes familiares claramente diferenciados, caracterizados por la corresidencia intergeneracional (caso latinoamericano, por la independencia (caso anglosajón y por la independencia (sólo residencial (caso latino-europeo. La convivencia entre miembros de la misma familia parece tener efectos positivos cuando no es por necesidad. La frecuencia de los contactos con otros miembros de la familia muestra un mayor efecto positivo cuanto mayor es la independencia de los adultos mayores.

Feasibility analysis of the application and positioning of DC HTS FCL in a DC microgrid through modeling and simulation using Simulink and SimPowerSystem

Energy Technology Data Exchange (ETDEWEB)

Khan, U.A.; Shin, W.J.; Seong, J.K.; Oh, S.H.; Lee, S.H. [School of Electrical Engineering and Computer Science, Hanyang University, Ansan-Shi, Gyeonggi-do 426-791 (Korea, Republic of); Lee, B.W., E-mail: bangwook@hanyang.ac.kr [School of Electrical Engineering and Computer Science, Hanyang University, Ansan-Shi, Gyeonggi-do 426-791 (Korea, Republic of)

2011-11-15

We modeled DC SFCL by use of SimPowerSystem blocks. We examine the DC fault current limitation in low voltage DC distribution networks. SFCL's affects at critical points were measured. SFCL installed at the substation rectifier branch resulted in abnormal increase of fault current. The strategic location of SFCL is the point of integration of the PV plant with the power grid. DC fault current limitation in DC distribution network is one of the critical issues which need to be taken care of before they can be practically implemented. High temperature superconductors could be efficiently installed to cope with the problem of DC fault currents. In this paper, a generalized DC high temperature superconducting fault current limiter (SFCL) is modeled by integrating Simulink and SimPowerSystem blocks. This model is designed for limiting DC fault currents in low voltage DC distribution networks. A DC microgrid having a low voltage DC distribution network, an integrated photovoltaic plant and domestic customer load is modeled. Transient analysis of the DC microgrid is performed by generating fault and measuring DC fault currents at critical points. The designed DC SFCL is placed at different strategic locations in DC microgrid and fault current limitation performance of DC SFCL in DC microgrid has been analyzed. Moreover, the affects of rapid impedance changing in the distribution network due to the fault followed by DC SFCL activation is investigated. Finally, the best suitable position and affects of DC SFCL in a DC microgrid along with suggestions for implementation have been proposed.

Feasibility analysis of the application and positioning of DC HTS FCL in a DC microgrid through modeling and simulation using Simulink and SimPowerSystem

International Nuclear Information System (INIS)

Khan, U.A.; Shin, W.J.; Seong, J.K.; Oh, S.H.; Lee, S.H.; Lee, B.W.

2011-01-01

We modeled DC SFCL by use of SimPowerSystem blocks. We examine the DC fault current limitation in low voltage DC distribution networks. SFCL's affects at critical points were measured. SFCL installed at the substation rectifier branch resulted in abnormal increase of fault current. The strategic location of SFCL is the point of integration of the PV plant with the power grid. DC fault current limitation in DC distribution network is one of the critical issues which need to be taken care of before they can be practically implemented. High temperature superconductors could be efficiently installed to cope with the problem of DC fault currents. In this paper, a generalized DC high temperature superconducting fault current limiter (SFCL) is modeled by integrating Simulink and SimPowerSystem blocks. This model is designed for limiting DC fault currents in low voltage DC distribution networks. A DC microgrid having a low voltage DC distribution network, an integrated photovoltaic plant and domestic customer load is modeled. Transient analysis of the DC microgrid is performed by generating fault and measuring DC fault currents at critical points. The designed DC SFCL is placed at different strategic locations in DC microgrid and fault current limitation performance of DC SFCL in DC microgrid has been analyzed. Moreover, the affects of rapid impedance changing in the distribution network due to the fault followed by DC SFCL activation is investigated. Finally, the best suitable position and affects of DC SFCL in a DC microgrid along with suggestions for implementation have been proposed.

A DC-DC Converter with Wide Input Voltage Range for Fuel Cell and Supercapacitor Application

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

2009-01-01

This paper proposes a novel phase-shift plus duty cycle controlled hybrid bi-directional DC-DC converter based on fuel cells and supercapacitors. The described converter employs two high frequency transformers to couple the half-bridge and full-bridge circuits together in the primary side...

Step-Up Partial Power DC-DC Converters for Two-Stage PV Systems with Interleaved Current Performance

Directory of Open Access Journals (Sweden)

Jaime Wladimir Zapata

2018-02-01

Full Text Available This work presents a partial power converter allowing us to obtain, with a single DC-DC converter, the same feature as the classical interleaved operation of two converters. More precisely, the proposed topology performs similarly as the input-parallel output-series (IPOS configuration reducing the current ripple at the input of the system and dividing the individual converters power rating, compared to a single converter. The proposed topology consists of a partial DC-DC converter processing only a fraction of the total power, thus allowing high efficiency. Experimental results are provided to validate the proposed converter topology with a Flyback-based 100 W test bench with a transformer turns ratio n 1 = n 2 . Experimental results show high performances reducing the input current ripple around 30 % , further increasing the conversion efficiency.

DC8 and DC13 var genes associated with severe malaria bind avidly to diverse endothelial cells.

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Marion Avril

Full Text Available During blood stage infection, Plasmodium falciparum infected erythrocytes (IE bind to host blood vessels. This virulence determinant enables parasites to evade spleen-dependent killing mechanisms, but paradoxically in some cases may reduce parasite fitness by killing the host. Adhesion of infected erythrocytes is mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1, a family of polymorphic adhesion proteins encoded by var genes. Whereas cerebral binding and severe malaria are associated with parasites expressing DC8 and DC13 var genes, relatively little is known about the non-brain endothelial selection on severe malaria adhesive types. In this study, we selected P. falciparum-IEs on diverse endothelial cell types and demonstrate that DC8 and DC13 var genes were consistently among the major var transcripts selected on non-brain endothelial cells (lung, heart, bone marrow. To investigate the molecular basis for this avid endothelial binding activity, recombinant proteins were expressed from the predominant upregulated DC8 transcript, IT4var19. In-depth binding comparisons revealed that multiple extracellular domains from this protein bound brain and non-brain endothelial cells, and individual domains largely did not discriminate between different endothelial cell types. Additionally, we found that recombinant DC8 and DC13 CIDR1 domains exhibited a widespread endothelial binding activity and could compete for DC8-IE binding to brain endothelial cells, suggesting they may bind the same host receptor. Our findings provide new insights into the interaction of severe malaria adhesive types and host blood vessels and support the hypothesis that parasites causing severe malaria express PfEMP1 variants with a superior ability to adhere to diverse endothelial cell types, and may therefore endow these parasites with a growth and transmission advantage.

Patronage or Signaling: How Mayors Use City Payroll to Stay in Office

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Vobolevičius Vincentas

2016-12-01

Full Text Available Several studies on municipal hiring decisions have indicated that when a city’s payroll grows, its mayor’s re-election prospects are likely to improve. It is not clear, however, if such an effect is attributable to patronage-driven, or signaling-driven, behavior of the incumbents. The difference is important: patronage leads to inefficient public administration, while signaling can produce political business cycles. In this paper, I propose some key electoral implications of patronage-driven and signaling-driven hiring, and verify them with data on local elections in Bulgaria (2015 and 2011 and in Poland (2014. I find that a large municipal workforce has a negative overall effect on mayors’ re-election. Importantly, the impact of city payroll varies with incumbents’ partisanship (strongly negative for mayors representing the economic right, neutral for independent mayors, positive for ex-communist mayors and does not depend on the duration of incumbent’s tenure. These findings strongly support the patronage-driven explanation of Eastern Europe’s local political economy.

Performance analysis of pulse analog control schemes for LLC resonant DC/DC converters suitable in portable applications

Directory of Open Access Journals (Sweden)

P. Kowstubha

2016-12-01

Full Text Available Performance Analysis of Pulse Analog Control Schemes, predominantly Pulse-Width Modulation (PWM and Pulse-Position Modulation (PPM for LLC resonant DC/DC converter suitable in portable applications is addressed in this paper. The analysis is done for closed loop performance, frequency domain performance, primary and secondary side conduction losses and soft commutation using PSIM 6.0 software and observed that PPM scheme provides better performance at high input voltage with a good selectivity of frequency over a wide range of line and load variations. The performance of LLC resonant DC/DC converter is demonstrated using PPM scheme for a design specifications of 12 V, 5 A output.

State-plane analysis of zero-voltage-switching resonant dc/dc power converters

Science.gov (United States)

Kazimierczuk, Marian K.; Morse, William D.

The state-plane analysis technique for the zero-voltage-switching resonant dc/dc power converter family of topologies, namely the buck, boost, buck-boost, and Cuk converters is established. The state plane provides a compression of information that allows the designer to uniquely examine the nonlinear dynamics of resonant converter operation. Utilizing the state plane, resonant converter modes of operation are examined and the switching frequencies are derived for the boundaries between these modes, including the boundary of energy conversion.

Cost-based droop scheme for DC microgrid

DEFF Research Database (Denmark)

Nutkani, Inam Ullah; Wang, Peng; Loh, Poh Chiang

2014-01-01

voltage level, less on optimized operation and control of generation sources. The latter theme is perused in this paper, where cost-based droop scheme is proposed for distributed generators (DGs) in DC microgrids. Unlike traditional proportional power sharing based droop scheme, the proposed scheme......-connected operation. Most importantly, the proposed scheme can reduce overall total generation cost in DC microgrids without centralized controller and communication links. The performance of the proposed scheme has been verified under different load conditions.......DC microgrids are gaining interest due to higher efficiencies of DC distribution compared with AC. The benefits of DC systems have been widely researched for data centers, IT facilities and residential applications. The research focus, however, has been more on system architecture and optimal...

Novel Step-Up DC/DC Converter with No Right Half Plane Zero and Reduced Switched Voltage Stress Characteristics

DEFF Research Database (Denmark)

Mostaan, Ali; Alizadeh, Ebrahim; Soltani, Mohsen

2014-01-01

and the voltage transfer gain is obtained. It is also demonstrated that the voltage stress on all semiconductor devices is restricted to input voltage which allows the utilization of a power switch with lower drain source resistance. In order to further increase the voltage gain another switched capacitor voltage......Novel step-up DC/DC converter is introduced in this paper. This converter is realized with adding the switched capacitor voltage multiplier cell to the three switch step-down DC/DC converter that has been proposed in the literature. The proposed converter is analyzed in the steady state...

Descubriendo los sentimientos y comportamientos que experimenta el adulto mayor con dolor crónico benigno

Directory of Open Access Journals (Sweden)

Alejandra María Alvarado García

Full Text Available Objetivo: Describir los comportamientos y sentimientos que experimentan los adultos mayores no institucionalizados frente al dolor crónico benigno. Métodos: Estudio cualitativo tipo teoría fundamentada a 25 adultos mayores con dolor crónico benigno residentes en las ciudades de Medellín y Bogotá. La técnica utilizada para recolectar la información fue la entrevista en profundidad. El análisis se hizo utilizando las herramientas de la teoría fundamentada bajo los lineamientos de Strauss y Corbin. Resultados: El estudio arrojó dos categorías principales, las cuales se nutren de códigos que dan muestra de los comportamientos y sentimientos percibidos por los adultos mayores. El adulto mayor decide expresar su comportamiento a través del llanto, la manipulación frente a los miembros de su familia, mientras que otros al contrario lo callan y esconden su dolor frente a la familia. Aparecen una serie de sentimientos y emociones como la angustia, la tristeza, el miedo, el estrés, la impotencia, la desesperanza y el aislamiento, los cuales dan cuenta de una nueva perspectiva que lleva a entender aún más cómo la experiencia del dolor crónico impacta en todas las dimensiones de los adultos mayores. Conclusiones: El estudio permitió describir los comportamientos y sentimientos de los adultos mayores no institucionalizados frente al dolor crónico benigno y a su experiencia con los servicios de salud. Esta mezcla de emociones sugiere un posterior agotamiento físico y mental en el adulto mayor despojándolo de toda su energía y arrastrándolo a experimentar emociones negativas que agudizarán sus síntomas y afectarán a otras funciones normales de su cuerpo.

Circuit description of unipolar DC-to-DC converters for APS storage ring quadrupoles and sextupoles

International Nuclear Information System (INIS)

McGhee, D.G.

1993-01-01

This paper describes the control, interlock, and power circuits for 680 unipolar switch mode DC-to-DC converters used to regulate the Advanced Photon Sources (APS's) storage ring quadrupole and sextupole magnet currents. Quadrupole current stability is ± 6x10 -5 and the sextupole current stability is ±3x10 -4 . The stability is obtained with pulse width modulation, operating at a switching frequency of 20kHz with full current switching. The converters are housed in 200 cabinets located on top of the storage ring tunnel. Raw DC power is distributed from 80 AC-to-DC power supplies, four at each of 20 locations around the storage ring. Voltages, currents, and temperatures are computer monitored and logged for the converters and magnets. All converters and magnets are water cooled with the flow and pressure monitored at the inlet and outlet of groups. Water is interlocked with the raw power supplies and not the individual converters

Chaos control in solar fed DC-DC boost converter by optimal parameters using nelder-mead algorithm powered enhanced BFOA

Science.gov (United States)

Sudhakar, N.; Rajasekar, N.; Akhil, Saya; Jyotheeswara Reddy, K.

2017-11-01

The boost converter is the most desirable DC-DC power converter for renewable energy applications for its favorable continuous input current characteristics. In other hand, these DC-DC converters known as practical nonlinear systems are prone to several types of nonlinear phenomena including bifurcation, quasiperiodicity, intermittency and chaos. These undesirable effects has to be controlled for maintaining normal periodic operation of the converter and to ensure the stability. This paper presents an effective solution to control the chaos in solar fed DC-DC boost converter since the converter experiences wide range of input power variation which leads to chaotic phenomena. Controlling of chaos is significantly achieved using optimal circuit parameters obtained through Nelder-Mead Enhanced Bacterial Foraging Optimization Algorithm. The optimization renders the suitable parameters in minimum computational time. The results are compared with the traditional methods. The obtained results of the proposed system ensures the operation of the converter within the controllable region.

Estereotipos negativos hacia la vejez en personas mayores de Latinoamérica

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Viviana X. Lasagni Colombo

2014-03-01

Full Text Available Introducción: Los objetivos del estudio se centran en investigar la presencia de estereotipos hacia la vejez en adultos mayores de diez países de Latinoamérica. Comparar el nivel de estereotipos entre países y evaluar la influencia de variables socio-demográficas en la formación de estereotipos. Metodología: Se realizó un estudio descriptivo transversal en adultos mayores de 60 a 70 años (N: 965 residentes en diez países de Latinoamérica. Se aplicó el Cuestionario de Estereotipos Negativos hacia la Vejez (CENVE y se estudió las posibles asociaciones entre variables socio demográficas y los factores del CENVE a través del análisis de varianzas (ANOVA. Los resultados demuestran que existen estereotipos negativos hacia la vejez en las personas mayores siendo más baja la presencia de estos en el factor motivacional. Se comprobó la relación significativa con variables “ocupación” y “nivel de escolaridad” y se corroboró la diferencia en la presencia de estereotipos negativos hacia la vejez entre los países que conforman este estudio. Conclusión: existen estereotipos negativos hacia la vejez en las personas mayores con diferencias entre grupos de países fundamentalmente por las condiciones sociosanitarias, educativas y económicas por las que atraviesan. El nivel de escolaridad y la situación socioeconómica influyen en la construcción de estereotipos negativos hacia la vejez.

Mayors and Public Education: The Case for Greater Involvement

Science.gov (United States)

Usdan, Michael D.

2006-01-01

Over the last generation, a new politics of education has evolved throughout the United States. Since the 1983 watershed report "A Nation at Risk" (National Commission on Excellence in Education, 1983), the country's most influential business and political leaders--and, more recently, mayors--have spearheaded efforts to improve student achievement…

Manifestaciones de violencia intrafamiliar hacia adultos mayores diabéticos. Pinar del Rio, 2012

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María de la Caridad Casanova Moreno

Full Text Available Introducción: la violencia contra el adulto mayor es un problema que requiere de sensibilización por parte del equipo de salud para ser visualizado. Objetivo: caracterizar las manifestaciones de violencia intrafamiliar hacia el adulto mayor diabético en un consultorio de la provincia de Pinar del Río. Métodos: se realizó un estudio descriptivo transversal durante el primer semestre del año 2012, en el Consultorio número 10 del Policlínico Universitario "Hermanos Cruz". El universo (U=86 estuvo constituido por el total de adultos mayores diabéticos; la muestra quedó conformada por 52 adultos mayores diabéticos. Las variables estudiadas fueron: edad, sexo, tipo de maltrato recibido, notificación, principal agresor e identificar la necesidad de información sobre el tema. Para la recolección de información se diseñó y aplicó un cuestionario por el equipo de investigación. Se utilizó el porcentaje como medida de resumen. Resultados: el grupo de edad más maltratado fue el de 60 a 69 años, predominando el sexo femenino. Los agresores más cercanos resultaron ser los hijos. La muestra estudiada manifestó que existe una insuficiente divulgación sobre el tema. Conclusiones: en el consultorio donde se realizó la investigación existen manifestaciones de violencia intrafamiliar en adultos mayores diabéticos, a pesar de que la comunidad no la reconoce como uno de sus problemas de salud.

El adulto mayor en cirugía general

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Armando Quintana Proenza

2001-12-01

Full Text Available Se realizó un estudio descriptivo y transversal con 249 pacientes de 60 y más años de edad operados en el Servicio de Cirugía General de los hospitales Clinicoquirúrgico Docente "Amalia Simoni" y General Docente "Martín Chang Puga" de la provincia Camagüey en un bienio. Más de la mitad de los pacientes tenían entre 60 y 69 años de edad, con predominio del sexo masculino, en una relación de 1,9:1. El mayor número de cirugía de urgencia se realizó en personas mayores de 70 años. La hernia de la pared abdominal fue el diagnóstico operatorio más frecuente (49 %. La hipertensión arterial constituyó la enfermedad asociada de mayor relevancia. La sepsis predominó entre las complicaciones posoperatorias. La mortalidad global fue de 16,87 %. Más del 70 % de los pacientes pudo haber sido operado en edades más tempranas de la vida de haber recibido una orientación médica adecuada.A descriptive cross-sectional study was conducted among 249 patients aged 60 and over that were operated on at the Service of General Surgery of "Amalia Simoni" Clinical and Surgical Teaching Hospital and "Martín Chang Puga" General Teaching Hospital, in the province of Camagüey, in a biennium. More than half of the patients were aged 60-69, with predominance of males in a ratio 1.9:1.The highest number of emergency surgery was performed in individuals over 70. The hernia of the abdominal wall was the most frequent surgical diagnosis (49 %. Arterial hypertension was the most important associated disease. Sepsis prevailed among the postoperative complications. Total mortality was 16.87 %. More than 70 % of the patients could have been operated when they were younger if they had received an adequate medical guidance.

Small-Signal Analysis of Single-Phase and Three-phase DC/AC and AC/DC PWM Converters with the Frequency-Shift Technique

DEFF Research Database (Denmark)

Blaabjerg, Frede; Aquila, A. Dell’; Liserre, Marco

2004-01-01

of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters......A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...... is to minimize the input admittance in order to make the grid converter more robust to grid disturbance....

Design and Control of a Multiple Input DC/DC Converter for Battery/Ultra-capacitor Based Electric Vehicle Power System

DEFF Research Database (Denmark)

Schaltz, Erik; Li, Zhihao; Onar, Omer

2009-01-01

Battery/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC/DC converter, to regulate output voltage from different inputs. The proposed multi-input con......Battery/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC/DC converter, to regulate output voltage from different inputs. The proposed multi...

Design and Implementation of Battery Charger with Power Factor Correction Using Sepic Converter and Full-bridge DC-DC Converter

OpenAIRE

Efendi, Moh. Zaenal; Windarko, Novie Ayub; Amir, Moh. Faisal

2013-01-01

This paper presents a design and implementation of a converter which has a high power factor for battery charger application. The converter is a combination of a SEPIC converter and a full-bridge DC-DC converter connected in two stages of series circuit. The SEPIC converter works in discontinuous conduction mode and it serves as a power factor corrector so that the shape of input current waveform follows the shape of input voltage waveform. The full-bridge DC-DC converter serves as a regulato...

Periodically Swapping Modulation (PSM) Strategy for Three-Level (TL) DC/DC Converter with Balanced Switch Currents

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Zhang, Qi

2018-01-01

The asymmetrical modulation strategy is widely used in various types of three-level (TL) DC/DC converters, while the current imbalance among the power switches is one of the important issues. In this paper, a novel periodically swapping modulation (PSM) strategy is proposed for balancing the power...... switches’ currents in various types of TL DC/DC converters. In the proposed PSM strategy, the driving signals of the switch pairs are swapped periodically, which guarantees that the currents through the power switches are kept balanced in every two switching periods. Therefore, the proposed PSM...... strategy can effectively improve the reliability of the converter by balancing the power losses and thermal stresses among the power switches. The operation principle and performances of the proposed PSM strategy are analyzed in detail. Finally, the simulation and experimental results are presented...

Maltrato institucional a adultos mayores

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Miriam Rubio Acuña

Full Text Available El maltrato institucional se refiere a cualquier forma de abuso que ocurre en servicios dirigidos a los ancianos. Esta revisión bibliográfica muestra que el maltrato se presenta con mayor frecuencia en residencias de larga estadía y el tipo más frecuente es la negligencia. Los factores asociados son los que tienen relación con el residente y con el ambiente. Las principales estrategias son invertir recursos sociosanitarios, sensibilizar a la población respecto al maltrato de los ancianos, considerar las necesidades de estos, fortalecer la formación de pregrado de los profesionales de salud en este ámbito y realizar educación continua. El maltrato es un problema social que debe ser abordado de manera integral.

Exceso de peso y discapacidad en las personas mayores de la Argentina

OpenAIRE

Malena Monteverde

2015-01-01

El objetivo del presente trabajo es analizar la relación entre el exceso de peso y la condición de discapacidad en las personas mayores de la Argentina y evaluar en qué medida podría estar operando algún factor protector que reduzca o atenúe el efecto del exceso de peso sobre la pérdida de capacidades funcionales en las personas mayores de 64 años. Para ello se utilizan los microdatos de la Encuesta Nacional de Factores de Riesgo 2009. Con el objeto de medir la asociación entre sobrepeso, obe...

INCREMENTO DE LA AUTOESTIMA EN LOS ADULTOS MAYORES DE UN HOGAR DE JUBILADOS

OpenAIRE

Teresa de Jesús Mazadiego Infante; Janeth Calderón Reyes; Claudia Solares Mejía; Maribel Zárate Moreno; Lisseth Torres Vargas; Ángel de Jesús Coto Sampayo

2011-01-01

El objetivo de este trabajo fue probar la efectividad de las técnicas de relajación, terapia ocupacional y dinámicas grupales para mejorar la autoestima de los adultos mayores de una casa-hogar para jubilados. Al efecto, se trabajó con una muestra de 17 adultos mayores, a quienes se asignaron diversas actividades, como ejercicios musicales, juegos de mesa, manualidades y sesiones de intercambio de experiencias y expresión de sentimientos. Los resultados obtenidos muestran un incremento consid...

Distributed maximum power point tracking in photovoltaic applications: active bypass DC/DC converter

Directory of Open Access Journals (Sweden)

Carlos Andrés Ramos-Paja

2012-01-01

Full Text Available Se propone una estructura de desvío activo para maximizar la producción de potencia en sistemas fotovoltaicos bajo condiciones irregulares de operación, comparando su eficiencia con soluciones individuales y distribuidas basadas en convertidores DC/DC convencionales. Los análisis y simulaciones realistas demuestran las ventajas del nuevo convertidor de desvío activo sobre soluciones basadas en convertidores Boost, Buck y Buck-Boost.

Modelling, Simulation and Construction of a DC/DC Boost Power Converter: A School Experimental System

Science.gov (United States)

Silva-Ortigoza, R.; Silva-Ortigoza, G.; Hernandez-Guzman, V. M.; Saldana-Gonzalez, G.; Marcelino-Aranda, M.; Marciano-Melchor, M.

2012-01-01

We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders…

EL SINDROME VESTIBULAR EN EL ADULTO MAYOR

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Dr. Hamlet Suárez

2016-11-01

Full Text Available El vértigo, la inestabilidad y las caídas tienen una incidencia relevante en el adulto mayor, disminuye su calidad de vida y puede ser causa de muerte en esta población. Este artículo describe las presentaciones clínicas y el abordaje de la evaluación de la patología vestibular en este grupo de edad, utilizando diferentes instrumentos para el diagnóstico así como también las reglas generales del tratamiento.

Evaluación en farmacias comunitarias del estado nutricional de mayores de 65 años

Directory of Open Access Journals (Sweden)

Inés Mera Gallego

2017-06-01

Full Text Available Objetivos: Evaluar el estado nutricional de mayores de 65 años con diabetes, que acuden a la farmacia comunitaria y compararlo con el de personas no diabéticas. Método: Estudio observacional-transversal en farmacias españolas por farmacéuticos socios de Sefac, de 9 de noviembre a 9 de diciembre de 2015. Criterios de Inclusión: ≥65 años, en dos grupos: diabéticos y no diabéticos. Variables: características antropométricas, altura suelo-rodilla (cm, circunferencia braquial (cm, circunferencia de la pantorrilla (cm, diabetes (SÍ/NO y estado nutricional (cuestionario Mini Nutritional Assessment. Resultados: 1.078 mayores, 652 (60,5% mujeres de 75,5±7,4 años, 461 (42,8% diabéticos. 73,4% con sobrepeso/obesidad. IMC=28,6±4,8 sin diferencias significativas entre sexos, mayor en diabéticos (29,0±4,8 vs 28,3±4,8 p=0,0173. 7,5% de diabéticos malnutridos frente al 6,5% de no diabéticos. 39,2% de diabéticos en riesgo de malnutrición frente al 29,8% de no diabéticos. El porcentaje de mujeres en riesgo de malnutrición y/o malnutrición es superior al de hombres (46,3% vs 32,4% p<0,0001. Mayor en mujeres diabéticas frente no diabéticas (52,4% vs 39,3% p=0,0075. 73,1% de diabéticos consideran que tienen problemas de nutrición frente al 80,7% de los no diabéticos p=0,0132. El 30,0% de los diabéticos consideran mejor su estado de salud frente al 45,9% de los no diabéticos. Conclusiones: El 82% de mayores de 65 años presenta malnutrición y/o riesgo de malnutrición, mayor en diabéticos que en no diabéticos y en mujeres que en hombres. 3 de cada 4 mayores de 65 años tienen sobrepeso u obesidad, mayor en hombres que en mujeres, y entre diabéticos que en no diabéticos.

A review on DC/DC converter architectures for power fuel cell applications

International Nuclear Information System (INIS)

Kolli, Abdelfatah; Gaillard, Arnaud; De Bernardinis, Alexandre; Bethoux, Olivier; Hissel, Daniel; Khatir, Zoubir

2015-01-01

Highlights: • Different DC/DC power converter topologies for Fuel Cell systems are presented. • Advantages and drawbacks of the DC/DC power converter topologies are detailed. • Wide-BandGap semiconductors are attractive candidates for design of converters. • Wide-BandGap semiconductors improve efficiency and thermal limits of converters. • Different semiconductor technologies are assessed. - Abstract: Fuel cell-based power sources are attractive devices. Through multi-stack architecture, they offer flexibility, reliability, and efficiency. Keys to accessing the market are simplifying its architecture and each components. These include, among others, the power converter enabling the output voltage regulation. This article focuses on this specific component. The present paper gives a comprehensive overview of the power converter interfaces potentially favorable for the automotive, railways, aircrafts and small stationary domains. First, with respect to the strategic development of a modular design, it defines the specifications of a basic interface. Second, it inventories the best architecture opportunities with respect to these requirements. Based on this study, it fully designs a basic module and points out the outstanding contribution of the new developed silicon carbide switch technology. In conclusion, this review article exhibits the importance of choosing the right power converter architecture and the related technology. In this context it is highlighted that the output power interface can be efficient, compact and modular. In addition, its features enable a thermal compatibility with many ways of integrating this component in the global fuel cell based power source.

A single-phase embedded Z-source DC-AC inverter.

Science.gov (United States)

Kim, Se-Jin; Lim, Young-Cheol

2014-01-01

In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

Asociación entre envejecimiento exitoso y participación social en personas mayores chilenas

Directory of Open Access Journals (Sweden)

Lorena Gallardo-Peralta

Full Text Available Objetivos: Analizar la asociación entre la participación social y el envejecimiento exitoso en una muestra representativa de personas mayores chilenas. Método: Se dispone de una muestra de 777 personas mayores chilenas. Se utilizó el Inventario de envejecimiento exitoso (SAI y todos los sujetos de la muestra firmaron una carta de consentimiento informado. Se realizaron análisis bivariados (prueba t de Student para muestras independientes y prueba de χ² a través de los programas SPSS (versión 23. Resultados: Se confirma la asociación entre participación social y envejecimiento exitoso; asimismo, los resultados muestran diferencias estadísticamente significativas entre las personas mayores que participan y los que no participan en el proceso de envejecer con éxito. Quienes participan en grupos sociales envejecen con éxito. Conclusiones: La participación social es un recurso psicosocial relevante en la intervención social gerontológica, dada su asociación positiva con el bienestar general de las personas mayores.

Power Quality in DC Power Distribution Systems and Microgrids

Directory of Open Access Journals (Sweden)

Stephen Whaite

2015-05-01

Full Text Available This review paper discusses power quality considerations for direct current (DC electric power distribution systems, particularly DC microgrids. First, four selected sample DC architectures are discussed to provide motivation for the consideration of power quality in DC systems. Second, a brief overview of power quality challenges in conventional alternating current (AC distribution systems is given to establish the field of power quality. Finally, a survey of literature addressing power quality issues in DC systems is presented, and necessary power quality considerations in DC distribution system design and operation are discussed.

Family of Step-up DC/DC Converters with Fast Dynamic Response for Low Power Applications

DEFF Research Database (Denmark)

N. Soltani, Mohsen; Mostaan, Ali; Siwakoti, Yam Prasad

2016-01-01

This study presents a family of novel step-up DC/DC converters which do not have a right half plane zero in their transfer function resulting in faster dynamic behaviour of the converters under the load variation. In addition, the voltage stress on all the active switches and diodes is as low...

Ultra-Step-Up DC-DC Converter with Integrated Autotransformer and Coupled Inductor

DEFF Research Database (Denmark)

Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang

2016-01-01

This paper introduces a new single-switch nonisolated dc-dc converter with very high voltage transfer ratio and reduced semiconductor voltage stress. The converter utilizes an integrated autotransformer and a coupled inductor on the same core to achieve a high step-up voltage gain without extreme...... duty cycle. Further, an integrated passive regenerative circuit recycles the leakage energy of the coupled magnetics and transfer the leakage energy to the load, which helps to avoid high voltage spikes across the switch. This feature along with low stress on the switching device enables the designer...

Simultaneous distribution of AC and DC power

Science.gov (United States)

Polese, Luigi Gentile

2015-09-15

A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range

Directory of Open Access Journals (Sweden)

Wenzheng Xu

2017-10-01

Full Text Available Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS and Zero Voltage Switching (ZVS in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.

Multi-cell DC-DC converters : modelling, analysis and control

International Nuclear Information System (INIS)

Feki, M.; El Aroudi, A.; Robert, B.G.M.

2011-01-01

This paper is devoted to modeling of a two-cell DC/DC buck converter, to the analysis of its behavior and to the design of control methods that yield to improve its performances. Various numerical simulations and dynamical aspects of this system are illustrated in the time domain and in the parameter space. Without control, the system may present many undesirable behaviors such as sub-harmonics and chaotic oscillations. The proposed controllers are able to widen the stability range of the system. Optimum values of parameters giving rise to fast response while maintaining stable periodic behavior are given in closed form. However, it is detected that in a certain region of the parameter space, the stabilized periodic orbit may coexist with a chaotic attractor. Boundary between basins of attraction are obtained by means of numerical simulations.

Input-Parallel Output-Parallel Three-Level DC/DC Converters With Interleaving Control Strategy for Minimizing and Balancing Capacitor Ripple Currents

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Gong, Zheng

2017-01-01

In this paper, the input-parallel output-parallel (IPOP) three-level (TL) DC/DC converters associated with the interleaving control strategy are proposed for minimizing and balancing the capacitor ripple currents. The proposed converters consist of two four-switch half-bridge three-level (HBTL) DC...

BaltDC: purification, characterization and infrared spectroscopy of an antiplatelet DC protein isolated from Bothrops alternatus snake venom.

Science.gov (United States)

Matias, Mariana Santos; de Sousa, Bruna Barbosa; da Cunha Pereira, Déborah Fernanda; Dias, Edigar Henrique Vaz; Mamede, Carla Cristine Neves; de Queiroz, Mayara Ribeiro; Silva, Anielle Christine Almeida; Dantas, Noelio Oliveira; Soares, Andreimar Martins; de Oliveira Costa, Júnia; de Oliveira, Fábio

2017-01-01

Snake venoms are a complex mixture of proteins, organic and inorganic compounds. Some of these proteins, enzymatic or non-enzymatic ones, are able to interact with platelet receptors, causing hemostatic disorders. The possible therapeutic potential of toxins with antiplatelet properties may arouse interest in the pharmacological areas. The present study aimed to purify and characterize an antiplatelet DC protein from Bothrops alternatus snake venom. The protein, called BaltDC (DC protein from B. alternatus snake venom), was purified by a combination of ion-exchange chromatography on DEAE-Sephacel column and gel filtration on Sephadex G-75. The molecular mass was estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). The amino acid sequence of the N-terminal region was carried out by Edman degradation method. Platelet aggregation assays were performed in human platelet-rich plasma (PRP). Infrared (IR) spectroscopy was used in order to elucidate the interactions between BaltDC and platelet membrane. BaltDC ran as a single protein band on SDS-PAGE and showed apparent molecular mass of 32 kDa under reducing or non-reducing conditions. The N-terminal region of the purified protein revealed the amino acid sequence IISPPVCGNELLEVGEECDCGTPENCQNECCDA, which showed identity with other snake venom metalloproteinases (SVMPs). BaltDC was devoid of proteolytic, hemorrhagic, defibrinating or coagulant activities, but it showed a specific inhibitory effect on platelet aggregation induced by ristocetin and epinephrine in PRP. IR analysis spectra strongly suggests that PO 3 2- groups, present in BaltDC, form hydrogen bonds with the PO 2 - groups present in the non-lipid portion of the membrane platelets. BaltDC may be of medical interest since it was able to inhibit platelet aggregation.

Simulation analysis of cascade controller for DC-DC bank converter

International Nuclear Information System (INIS)

Mahar, M.A.; Abro, M.R.; Larik, A.S.

2009-01-01

Power electronic converters are periodic variable structure systems due to their switched operation. During the last few decades several new dc-dc converter topologies have emerged. Buck converter being simple in topology, has recently drawn attraction of many researchers. Basically, a buck converter is highly underdamped system. In order to overcome the developed oscillations in output of this converter, various control techniques have been proposed. However, these techniques are fraught with many drawbacks. This paper focus on a cascade controller based buck topology. Steady state analysis is given in this paper which shows output voltage and inductor current in detail. Dynamic analysis for line and load variation is also presented. The buck topology is implemented and simulated in MATLAB/Simulink. The simulated results are presented. (author)

Bidirectional dc-to-dc Power Converter

Science.gov (United States)

Griesbach, C. R.

1986-01-01

Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

Pulsed dc self-sustained magnetron sputtering

International Nuclear Information System (INIS)

Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

2008-01-01

The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm 2 . The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition

Troubleshooting of Modulator DC power supply at KOMAC

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae Seong; Kim, Han Sung; Kwon, Hyeok Jung; Kim, Seong Gu; Kim, Dae Il; Lee, Seok Geun; Kim, Jae Ha; Seol, Kyeong Tae; Cho, Yong Sub [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The process of solving problems to operate the 2nd converter modulator will be introduced. Also, the PSpice simulation result about the 12-pulse rectifier will be compared with the measurement result. KOMAC (KOrea Multi-purpose Accelerator Complex) has four HVCMs (High Voltage Converter Modulator) which are the power source of nine klystrons. Four HVCMs are already operated since 2013 for operating the 100 MeV linear proton accelerator at KOMAC. This HVCM system includes the 12-pulse rectifier (ac-dc), capacitors bank (dc-link, Pos, Neg) and converter modulator (dc-dc). Especially, the 12-pulse rectifier system receives the power from the utility and converts 3,300 ac voltage to 2,200 dc voltage for supplying the dc power to the capacitors bank. This rectifier system used twelve thyristors for the rectification and applied RC snubber networks to protect the semiconductor switches (thyristors). Since the 2nd modulator dc power supply has troubled, the troubleshooting process conducted by the staves of KOMAC. It takes 3 months to solve the problems because it is not easy to find the faulty wiring. Nevertheless, our staves found the faulty point with a hope to operate the modulator system and the PSpice simulation helps to solve the problems. Using PSpice which is tool for simulating the circuit, the dc power supply abnormal phenomenon was simulated exactly. After corrected the faulty wiring, the modulator dc power supply operated.

Riesgo de deterioro cognitivo en personas mayores de las subregiones de Antioquia, Colombia

Directory of Open Access Journals (Sweden)

Angela Segura Cardona

Full Text Available Resumen En este artículo, se buscó conocer la prevalencia de riesgo de deterioro cognitivo y su relación con factores demográficos, sociales y funcionales en las personas mayores de las subregiones de Antioquia, Colombia. Se trata de un estudio cuantitativo, transversal analítico, con fuente de información primaria. La muestra fue probabilística y se determinó el riesgo de deterioro cognitivo con la escala minimental. Así se encontró que el 83,1% de los mayores presenta algún riesgo de deterioro cognitivo, principalmente las mujeres, y está asociado significativamente con vivir en la subregión del Magdalena Medio y Medellín, tener mayor edad, no tener pareja, no tener escolaridad, tener escasos recursos sociales, no participar en grupos comunitarios, tener mala percepción de la calidad de vida, estar insatisfecho con la salud y tener dependencia funcional para realizar las actividades básicas. Estos resultados permiten orientar los programas de salud pública relacionados con la inclusión de las personas mayores hacia programas educativos, la participación en grupos comunitarios, la tamización constante en los servicios de salud, el fortalecimiento de los recursos sociales y el fomento de la actividad física en la vejez, para lograr un envejecimiento saludable con mejor calidad de vida.

La obesidad en las personas mayores, un problema de salud pública

OpenAIRE

Abellán García, Antonio

2016-01-01

La obesidad es un serio problema de salud pública. Se suele medir utilizando el Índice de Masa Corporal. En España, un 23,6% de las personas mayores (65 y más años) tiene obesidad, y otro 45,0% sobrepeso, según la última Encuesta Europea de Salud (2014). Sólo un 30,0% está en un peso normal. En el resto de adultos también se observa esta circunstancia. Es decir, en España existe un problema de sobrepeso y obesidad, especialmente entre los mayores y estas cifras son peores que la media de la ...

Intervención de trabajo social con adultos mayores

Directory of Open Access Journals (Sweden)

Yesica Rodríguez Montañez

2003-01-01

Full Text Available El artículo presenta las metodologías de intervención del Trabajo Social con adultos mayores realizando un recorrido por los términos envejecimiento y vejez, haciendo énfasis en la importancia de la pérdida en la concepción de la misma . Se realiza un aná

Salud y calidad de vida en adultos mayores de un área rural y urbana del Perú

Directory of Open Access Journals (Sweden)

Jean Hernandez-Huayta

Full Text Available RESUMEN Objetivos. Evaluar la calidad de vida relacionada a salud en una muestra de la población adulta mayor de un área rural y urbana del Perú. Materiales y métodos. Estudio transversal en población adulta mayor de cuatro distritos rurales y uno urbano realizado entre octubre del año 2014 a enero de 2016. Se evaluó la asociación entre el área de residencia y cinco variables sociodemográficas mediante la prueba de chi cuadrado. Utilizando la prueba de suma de rangos de Wilcoxon y evaluando magnitud de efectos se midieron y compararon los puntajes por dimensiones obtenidos en los instrumentos WHOQOL-BREF y WHOQOL-OLD y el puntaje total de este último. Se realizó regresión lineal simple y múltiple para hallar los valores ajustados a las diferencias sociodemográficas. Resultados. Se encuestaron a 447 adultos mayores con una media de edad de 69 años (+ 6,46 años, 207 del área rural, los cuales, en su mayoría, trabajaban y tenían menos años de educación. La población adulta mayor del área rural tuvo mayor calidad de vida en las dimensiones "Física", "Psicológico" y "Medioambiente" del WHOQoL-BREF y en "Habilidades sensoriales", "Autonomía", "Actividades del pasado, presente y futuro", "Participación social" y en el puntaje total del WHOQoL-OLD; mientras que aquellos del área urbana sólo mostraron mayor calidad de vida en la dimensión "Intimidad". Conclusiones. El área de residencia ejerce un efecto diferencial en las distintas dimensiones de la calidad de vida relacionada a salud de la población adulta mayor estudiada.

Salud y calidad de vida en adultos mayores de un área rural y urbana del Perú

Directory of Open Access Journals (Sweden)

Jean Hernandez-Huayta

Full Text Available Objetivos. Evaluar la calidad de vida relacionada a salud en una muestra de la población adulta mayor de un área rural y urbana del Perú. Materiales y métodos. Estudio transversal en población adulta mayor de cuatro distritos rurales y uno urbano realizado entre octubre del año 2014 a enero de 2016. Se evaluó la asociación entre el área de residencia y cinco variables sociodemográficas mediante la prueba de chi cuadrado. Utilizando la prueba de suma de rangos de Wilcoxon y evaluando magnitud de efectos se midieron y compararon los puntajes por dimensiones obtenidos en los instrumentos WHOQOL-BREF y WHOQOL-OLD y el puntaje total de este último. Se realizó regresión lineal simple y múltiple para hallar los valores ajustados a las diferencias sociodemográficas. Resultados. Se encuestaron a 447 adultos mayores con una media de edad de 69 años (+ 6,46 años, 207 del área rural, los cuales, en su mayoría, trabajaban y tenían menos años de educación. La población adulta mayor del área rural tuvo mayor calidad de vida en las dimensiones "Física", "Psicológico" y "Medioambiente" del WHOQoL-BREF y en "Habilidades sensoriales", "Autonomía", "Actividades del pasado, presente y futuro", "Participación social" y en el puntaje total del WHOQoL-OLD; mientras que aquellos del área urbana sólo mostraron mayor calidad de vida en la dimensión "Intimidad". Conclusiones. El área de residencia ejerce un efecto diferencial en las distintas dimensiones de la calidad de vida relacionada a salud de la población adulta mayor estudiada.

Morbilidad cardiovascular en el adulto mayor

Directory of Open Access Journals (Sweden)

Rita Campillo Motilva

2001-12-01

Full Text Available Se realizó un estudio transversal y descriptivo, con el objetivo de definir la morbilidad por enfermedad cardiovascular en pacientes de 60 años y más, en un consultorio médico perteneciente al Policlínico Docente "Dr. Mario Escalona Reguera" del municipio Habana del Este, en el período entre marzo y diciembre del año 2000. Fueron incluidos 69 pacientes, 52 de los cuales (75,3 % presentó algún tipo de enfermedad cardiovascular, y fue el sexo femenino el más afectado (51,9 %. La enfermedad que se encontró con mayor frecuencia fue la hipertensión arterial (43 pacientes para un 62,3 %, observamos que la sistodiastólica (86,1 % y el estadio II (53,5 % fue donde se incluyeron mayor número de individuos. Otras enfermedades encontradas fueron los trastornos electrocardiográficos (33 pacientes para un 47,8 % y valvulopatías (18 pacientes para un 26 %.A cross-sectional and descriptive study was conducted in order to define morbidity due to cardiovascular disease in patients aged 60 and over in a family physician’s office of "Dr. Mario Escalona Reguera" Teaching Polyclinic, in Habana del Este municipality, from March to December, 2000. 69 patients were included. 52 of them (75.3 % had some type of cardiovascular disease and females were the most affected (51.9 %. Arterial hypertension was the most commonly found disease (43 patients for 62.3 %. Most of the individuals were included in the systodiastolic (86.1 % and in stage II (53.5 %. Electrocardiographic disorders (33 patients for 47.8 % and valvulopathies (18 patients for 26 % were other of the diseases detected.

Factores de bienestar laboral : percepción de los trabajadores de mayor edad /

OpenAIRE

González Gómez de Olmedo, María Paz

2014-01-01

Introducción: La situación demográfica y económica Europea, con la consecuente prolongación de la vida laboral, plantea la necesidad de desarrollar estratégias que permitan, a los trabajadores mayores, conservar la capacidad de trabajo, con salud y bienestar. Objetivos de investigación: - Identificar, empíricamente, en contextos laborales específicos, los factores que, desde la percepción de los trabajadores mayores, estan relacionados con el bienestar y la intención de continuar laboralmente...

Geometry Optimization of DC/RF Photoelectron Gun

CERN Document Server

Chen Ping; Yu, David

2005-01-01

Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

La calidad de vida de los sujetos usuarios de un centro social de personas mayores

Directory of Open Access Journals (Sweden)

César Bugallo Carrera

2014-09-01

Full Text Available En esta investigación hemos intentado comprobar si la asistencia a los centros sociales de personas mayores es un medio eficaz para la mejora de la calidad de vida de las personas mayores, es decir, si los usuarios de dichos centros tienen una mejor calidad de vida que aquellos que no acuden a ellos. Para ello, hemos contado con un grupo experimental y un grupo control. A continuación ambos grupos han pasado dos pruebas: una que valora la calidad de vida y otra, el deterioro cognitivo. Una vez pasadas las pruebas y obtenidas las puntuaciones, hemos concluido que los usuarios del centro social tienen una mayor calidad de vida que los sujetos que no acuden a él.

Modeling, Control and Protection of Low-Voltage DC Microgrids

OpenAIRE

Salomonsson, Daniel

2008-01-01

Current trends in electric power consumption indicate an increasing use of dc in end-user equipment, such as computers and other electronic appliances used in households and offices. With a dc power system, ac/dc conversion within these loads can be avoided, and losses reduced. AC/DC conversion is instead centralized, and by using efficient, fully controllable power-electronic interfaces, high power quality for both ac and dc systems during steady state and ac grid disturbances can be obtaine...

A ZVS PWM control strategy with balanced capacitor current for half-bridge three-level DC/DC converter

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Chen, Zhe

2017-01-01

The capacitor current would be imbalanced under the conventional control strategy in the half-bridge three-level (HBTL) DC/DC converter due to the effect of the output inductance of the power supply and the input line inductance, which would affect the converter's reliability. This paper proposes...... a pulse-wide modulation (PWM) strategy composed of two operation modes for the HBTL DC/DC converter, which can realize the zero-voltage switching (ZVS) for the efficiency improvement. In addition, a capacitor current balancing control is proposed by alternating the two operation modes of the proposed ZVS...... PWM strategy, which can eliminate the current imbalance among the two input capacitors. Therefore, the proposed control strategy can improve the converter's performance and reliability in: 1) reducing the switching losses and noises of the power switches; 2) balancing the thermal stresses...

The copal of the Chichen Itza offerings and of the Templo Mayor of Tenochtitlan; El copal de las ofrendas de Chichen Itza y del Templo Mayor de Tenochtitlan

Energy Technology Data Exchange (ETDEWEB)

Montufar L, A [Subdireccion de Laboratorios y Apoyo Academico INAH, Moneda No. 6, Col Centro, 06060 Mexico D.F. (Mexico); Gutierrez W, C E; Mendoza A, D [ININ, Carr. Mexico-Toluca s/n La Marquesa, 52750 Ocoyoacac, Estado de Mexico (Mexico); Torres M, A [Facultad de Ciencias, UNAM, A.P. 20-364 01000 Mexico D.F. (Mexico)

2006-07-01

Literature from the post conquest shows that the Mayans used copal resins in their religious celebrations and ceremonial rites, specially as a sahumerio material. Historical precedents have been fully documented, establishing its use in the calendar ceremonies performed by the Aztecs towards their agricultural practices, mainly for the corn crop; and that according to the registries of sacred figures of their gods, they were made out of copal resin. Abundant fragments of this resin were found in a number of offerings at the digging of the Templo Mayor of Tenochtitlan. These facts indicate the intensive use of the copal as a link with divinities of life, maintenance and fertility, among many other aspects of existence, as stated by the Mexicas cosmos view. In order to determine the possible origin of the different types of copal, small samples were analyzed by infrared spectroscopy, both from Chichen Itza and the pre hispanic from Templo Mayor of Tenochtitlan. Results show a great similarity between each absorption band, the one from Templo Mayor and the modern sample Bursera bipinnata and the one from Chichen Itza and the modem resin of Protium copal. This suggests that the pre hispanic copal form Chichen Itza was obtained from the Protium copal tree. (Author)

Novel family of quasi-Z-source DC/DC converters derived from current-fed push-pull converters

DEFF Research Database (Denmark)

Chub, Andrii; Husev, Oleksandr; Vinnikov, Dmitri

2014-01-01

This paper is devoted to the step-up quasi-Z-source dc/dc push-pull converter family. The topologies in the family are derived from the isolated boost converter family by replacing input inductors with the quasi-Z-source network. Two new topologies are proposed, analyzed and compared. Theoretical...

Suited for Spacewalking: A Teacher's Guide with Activities for Technology Education, Mathematics, and Science

Science.gov (United States)

Vogt, Gregory L.; George, Jane A. (Editor)

1998-01-01

A Teacher's Guide with Activities for Technology Education, Mathematics, and Science National Aeronautics and Space Administration Office of Human Resources and Education Education Division Washington, DC Education Working Group NASA Johnson Space Center Houston, Texas This publication is in the Public Domain and is not protected by copyright. Permission is not required for duplication.

75 FR 35611 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, and MD-10-10F...

Science.gov (United States)

2010-06-23

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, and MD-10-10F Airplanes... certain McDonnell Douglas Model DC-10-10, DC-10-10F, and MD-10-10F airplanes. That NPRM was published in... amends Sec. 39.13 by adding the following new AD: 2010-13-06 McDonnell Douglas Corporation: Amendment 39...

Active superconducting DC fault current limiter based on flux compensation

International Nuclear Information System (INIS)

Shi Jing; Tang Yuejin; Wang, Chen; Zhou Yusheng; Li Jingdong; Ren Li; Chen Shijie

2006-01-01

With the extensive application of DC power systems, suppression of DC fault current is an important subject that guarantees system security. This paper presents an active superconducting DC fault current limiter (DC-SFCL) based on flux compensation. The DC-SFCL is composed of two superconducting windings wound on a single iron core, the primary winding is in series with DC power system, and the second winding is connected with AC power system through a PWM converter. In normal operating state, the flux in the iron core is compensated to zero, and the SFCL has no influence on DC power system. In the case of DC system accident, through regulating the active power exchange between the SFCL's second winding and the AC power system, the current on the DC side can be limited to different level complying with the system demand. Moreover, the PWM converter that interface the DC system and AC system can be controlled as a reactive power source to supply voltage support for the AC side, which has little influence on the performance of SFCL. Using MATLAB SIMULINK, the mathematic model of the DC-SFCL is created, simulation results validate the dynamics of system, and the performance of DC-SFCL is confirmed

FACTORES BIOPSICOSOCIALES ASOCIADOS A LAS ACTIVIDADES DE LA VIDA COTIDIANA DEL ADULTO MAYOR. CENTRO DE SALUD SAN JUAN DEL DISTRITO DE PAUCARPATA.AREQUIPA, 2012

OpenAIRE

MACEDO VALENCIA, HILDA EMILIANA

2013-01-01

EL ADULTO MAYOR ETAPA EVOLUTIVA DEL ADULTO MAYOR CARACTERÍSTICAS DEL ADULTO MAYOR QUE TIENEN UN ENVEJECIMIENTO SALUDABLE IMPACTO DE LAS CONDICIONES PSICOSOCIALES EN EL ADULTO MAYOR FACTORES BIO-PSICO-SOCIALES FACTORES BIOLÓGICOS FACTORES PSICOLÓGICOS FACTORES SOCIALES ACTIVIDADES DE LA VIDA COTIDIANA DEL ADULTO MAYOR

A Decentralized Current-Sharing Controller Endows Fast Transient Response to Parallel DC-DC Converters

DEFF Research Database (Denmark)

Wang, Haojie; Han, Minxiao; Han, Renke

2018-01-01

This paper proposes a decentralized current-sharing control strategy to endow fast transient response to paralleled DC-DC converters systems, such as DC microgrids or distributed power systems. The proposed controller consist of two main control loops: an external voltage droop control for current......-sharing proposes and an internal current loop. The external droop control loop is designed as a voltage loop with embedded virtual impedance, which avoids the use of a slow voltage loop and a separate extra virtual impedance loop that may limit the system bandwidth. The internal current loop, thanks...... and the proposed embedded-virtual-impedance based I-V droop. In order to compare the dynamic response performances between two droop controllers, their state-space models have been developed and analyzed in this paper. The results show that the dynamic response of the I-V droop control is faster than...

A Reconfigurable Series Resonant DC-DC Converter for Wide-Input and Wide-Output Voltages

DEFF Research Database (Denmark)

Shen, Yanfeng; Wang, Huai; Qin, Zian

2017-01-01

This paper proposes a dual-bridge based LC series resonant dc-dc converter. The input inverter unit incorporates two bridge structures, i.e., a full-bridge inverter and a half-bridge inverter. For the output rectifier, it can be a full-bridge rectifier or an asymmetric half-bridge rectifier....... Different from the conventional resonant converter, a fixed-frequency PWM control is employed which makes the optimization of magnetic components easier. The primary-side switches can achieve ZVS and the secondary-side diodes turn off with ZCS. In addition, the root-mean-square (RMS) values...... of the transformer currents do not significantly vary with respect to the voltage variation. Therefore, this converter can maintain high efficiency over a wide voltage range. The topology and operating principle are firstly described. Then the dc voltage gain and the RMS current characteristics are detailed. Finally...

Modelling, simulation and construction of a dc/dc boost power converter: a school experimental system

International Nuclear Information System (INIS)

Silva-Ortigoza, R; Marciano-Melchor, M; Silva-Ortigoza, G; Hernández-Guzmán, V M; Saldaña-González, G; Marcelino-Aranda, M

2012-01-01

We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders the feasible introduction of this equipment in undergraduate laboratories. (paper)

Security analysis of interconnected AC/DC systems

DEFF Research Database (Denmark)

Eriksson, Robert

2015-01-01

This paper analyses N-1 security in an interconnected ac/dc transmission system using power transfer distribution factors (PTDFs). In the case of a dc converter outage the power needs to be redistributed among the remaining converter to maintain power balance and operation of the dc grid...... any line or transformer limits. Simulations were performed in a model of the Nordic power system where a dc grid is placed on top. The simulation supports the method as a tool to consider transfer limits in the grid to avoid violate the same and increase the security after a converter outage........ The redistribution of power has a sudden effect on the power-flow in the interconnected ac system. This may cause overloading of lines and transformers resulting in disconnection of equipment, and as a consequence cascading failure. The PTDF is used as a method to analyze and avoid violating limits by in the dc...

Systematic design approach of fuzzy PID stabilizer for DC-DC converters

International Nuclear Information System (INIS)

Guesmi, K.; Essounbouli, N.; Hamzaoui, A.

2008-01-01

DC-DC converters process electrical energy by switching between a fixed number of configurations. The objective of controlling these systems is to provide better performances, ensure closed loop stability and guarantee a simple predictable behaviour. Based on a converter averaged model, we propose, in this paper, a systematic design approach of a fuzzy PID. The choice of controller parameters stands on the whole system stability requirements. Extension of the obtained asymptotic stability to structural stability is presented to show that the developed controller ensures also a simple and predictable behaviour of the converter. Finally, we illustrate the efficiency of the proposed fuzzy PID design approach through simulations in voltage mode as well as in current mode control

Systematic design approach of fuzzy PID stabilizer for DC-DC converters

Energy Technology Data Exchange (ETDEWEB)

Guesmi, K.; Essounbouli, N.; Hamzaoui, A. [CReSTIC, IUT de Troyes 09, rue de Quebec BP. 396, 10026 Troyes (France)

2008-10-15

DC-DC converters process electrical energy by switching between a fixed number of configurations. The objective of controlling these systems is to provide better performances, ensure closed loop stability and guarantee a simple predictable behaviour. Based on a converter averaged model, we propose, in this paper, a systematic design approach of a fuzzy PID. The choice of controller parameters stands on the whole system stability requirements. Extension of the obtained asymptotic stability to structural stability is presented to show that the developed controller ensures also a simple and predictable behaviour of the converter. Finally, we illustrate the efficiency of the proposed fuzzy PID design approach through simulations in voltage mode as well as in current mode control. (author)

Deadbeat control of power leveling unit with bidirectional buck/boost DC/DC converter

OpenAIRE

Hamasaki, Shin-ichi; Mukai, Ryosuke; Yano, Yoshihiro; Tsuji, Mineo

2014-01-01

As a distributed generation system increases, a stable power supply becomes difficult. Thus control of power leveling (PL) unit is required to maintain the balance of power flow for irregular power generation. The unit is required to respond to change of voltage and bidirectional power flow. So the bidirectional buck/boost DC/DC converter is applied for the control of PL unit in this research. The PL unit with Electric double-layer capacitor (EDLC) is able to absorb change of power, and it is...

Conducted EMI Prediction and Mitigation Strategy Based on Transfer Function for a High-Low Voltage DC-DC Converter in Electric Vehicle

Directory of Open Access Journals (Sweden)

Li Zhai

2018-04-01

Full Text Available The high dv/dt and di/dt outputs from power devices in a high-low voltage DC-DC converter on electric vehicles (EVs can always introduce the unwanted conducted electromagnetic interference (EMI emissions. A conducted EMI prediction and mitigation strategy that is based on transfer function for the high-low voltage DC-DC converter in EVs are proposed. A complete test for the DC-DC converter is conducted to obtain the conducted EMI from DC power cables in the frequency band of 150 kHz-108 MHz. The equivalent circuit with high-frequency parasitic parameters of the DC-DC converter is built`1 based on the measurement results to acquire the characteristics of the conducted EMI of the DC power cables. The common mode (CM and differential mode (DM propagation coupling paths are determined, and the corresponding transfer functions of the DM interference and CM interference are established. The simulation results of the conducted EMI can be obtained by software Matlab and Computer Simulation Technology (CST. By analyzing the transfer functions and the simulation results, the dominated interference is the CM interference, which is the main factor of the conducted EMI. A mitigation strategy for the design of the CM interference filter based on the dominated CM interference is proposed. Finally, the mitigation strategy of the conducted EMI is verified by performing the conducted voltage experiment. From the experiment results, the conducted voltage of the DC power cables is decreased, respectively, by 58 dBμV, 55 dBμV, 65 dBμV, 53 dBμV, and 54 dBμV at frequency 200 kHz, 400 kHz, 600 kHz, 1.4 MHz, and 50 MHz. The conduced voltage in the frequency band of 150 kHz–108 MHz can be mitigated by adding the CM interference filters, and the values are lower than the limit level-3 of CISPR25 standard (GB/T 18655-2010.

Comparative efficiency evaluation of buck and hybrid buck DC-DC converters for automotive applications

DEFF Research Database (Denmark)

Pelan, Ovidiu; Cornea, Octavian; Muntean, Nicolae

2014-01-01

This paper presents and discusses design considerations and efficiency investigation of a conventional step-down and a hybrid switched-capacitor DC-DC converter. Three MOSFETs with low on-resistance have been tested for each converter in order to find the most adequate switch for this application....... The experimental results and comparative efficiency graphs were obtained with a 1kW laboratory prototype dedicated for a 42/14V dual voltage automotive system....

MEDOW - Multi-terminal DC Grid for Offshore Wind, Final report

DEFF Research Database (Denmark)

A DC grid based on multi-terminal voltage-source converter is a newly emerging technology, which is particularly suitable for the connection of offshore wind farms. Multi-terminal DC grids will be the key technology for the European offshore ‘Super Grid’. In the project, DC power flow, DC relaying...... protection, steady state operation, dynamic stability, fault-ride through capability, and impacts of DC grids on the operation of AC grids and power market were studied. Systematic comparison of DC grid topologies and stability control strategies was carried out, and DC grids for offshore wind power...

Kingsnorth-London dc transmission link

Energy Technology Data Exchange (ETDEWEB)

1966-03-11

The hvdc transmission link between one of the 500 MW generators at Kingsnorth Power Station and two receiving stations in London will use a three-wire dc cable system rated to carry 1200 A at +- 266 kV. This 51-mile system will be the first dc link in the world to be used as an integral part of a complex interconnected ac network.

Dual wound dc brush motor gearhead

Science.gov (United States)

Henson, Barrie W.

1986-01-01

The design requirements, the design, development tests and problems, the qualification and life test and the findings of the strip examination of a dual wound DC brushed motor gearhead are described. It is the only space qualified dual wound dc brushed motor gearhead in Europe.

Hipnosis como complemento en la cirugía oral del adulto mayor

Directory of Open Access Journals (Sweden)

Elina Muñiz Manzano

2013-03-01

Full Text Available Introducción: el envejecimiento poblacional es un fenómeno mundial y la cirugía oral es compleja en los adultos mayores, por lo que la preparación preoperatoria es de vital importancia para una evolución satisfactoria. Este trabajo tiene como objetivo demostrar la eficacia de la hipnosis en pacientes con temor en la cirugía oral del adulto mayor. Métodos: se realizó un estudio descriptivo, transversal, con muestra de 20 pacientes de 60 años o más, atendidos en la consulta de Cirugía Maxilofacial del Hospital Universitario "Comandante Manuel Fajardo", en el año 2011, donde se analizaron las variables edad, sexo, número de sesiones de hipnosis, antecedentes patológicos, diagnósticos más frecuentes y temor. Resultados: el mayor número de pacientes se encontró entre 60-69 años de edad, (70 % y el menor en 70-79, (30 %. El sexo femenino prevaleció con 70 %. El número de sesiones fue en el grupo de 60-69 con 58, con un promedio total de 4 por pacientes. En los antecedentes patológicos más frecuentes fue la hipertensión arterial en 14 (70 % y le siguió la diabetes tipo II en 2 (10 % En los diagnósticos más frecuentes fue la caries de cuarto grado con 10 (50 % seguido por los dientes parodontósicos con 4 (20 %. El temor se midió en una escala confeccionada, en la que los pacientes con cifras de l0, 8 y 7 se redujeron a 4 y 5. Conclusiones: Se demuestra la efectividad de la terapia de hipnosis para disminuir el temor y realizar la cirugía oral en el adulto mayor.

Analysis and Controller Design of a Universal Bidirectional DC-DC Converter

Directory of Open Access Journals (Sweden)

Kou-Bin Liu

2016-06-01

Full Text Available In this paper, first the operating principles of a non-isolated universal bidirectional DC-DC converter are studied and analyzed. The presented power converter is capable of operating in all power transferring directions in buck/boost modes. Zero voltage switching can be achieved for all the power switches through proper modulation strategy design, therefore, the presented converter can achieve high efficiency. To further improve the efficiency, the relationship between the phase-shift angle and the overall system efficiency is analyzed in detail, an adaptive phase-shift (APS control method which determines the phase-shift value between gating signals according to the load level is then proposed. As the modulation strategy is a software-based solution, there is no requirement for additional circuits, therefore, it can be implemented easily and instability and noise susceptibility problems can be reduced. To validate the correctness and the effectiveness of the proposed method, a 300 W prototyping circuit is implemented and tested. A low cost dsPIC33FJ16GS502 digital signal controller is adopted in this paper to realize the power flow control, DC-bus voltage regulation and APS control. According to the experimental results, a 12.2% efficiency improvement at light load and 4.0% efficiency improvement at half load can be achieved.

Drilling history core hole DC-6 Hanford, Washington

International Nuclear Information System (INIS)

1978-06-01

Core hole DC-6 was completed in May 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scisson, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-6. Core hole DC-6 is located within the boundary of the Hanford Site at the old Hanford town site. The Hanford Site coordinates for DC-6 are North 54,127.17 feet and West 17,721.00 feet. The surface elevation is approximately 402 feet above sea level. The purpose of core hole DC-6 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection and to provide a borehole for hydrologic testing. The total depth of core hole DC-6 was 4336 feet. Core recovery was 98.4% of the total footage cored

FPGA implementation of optimal and approximate model predictive control for a buck-boost DC-DC converter

NARCIS (Netherlands)

Spinu, V.; Oliveri, A.; Lazar, M.; Storace, M.

2012-01-01

This paper proposes a method for FPGA implementation of explicit, piecewise af¿ne (PWA) model predictive control (MPC) laws for non-inverting buck-boost DC-DC converters. A novel approach to obtain a PWA model of the power converter is proposed and two explicit MPC laws are derived, i.e., one based

Molecular characterization using ISSR primers of Magnolia mexicana DC. from two regions in Zongolica, Veracruz, Mexico

Directory of Open Access Journals (Sweden)

Jessica M. Medrano-Hernández

2017-01-01

Full Text Available Introducción: Magnolia mexicana DC . es una especie amenazada según la NOM-059-SEMARNAT-2010, situación atribuida a la fragmentación y destrucción del hábitat. No existen estudios sobre la diversidad genética de M. mexicana, a pesar de que es endémica de nuestro país. Objetivo: Evaluar la variabilidad genética en dos poblaciones de M. mexicana mediante marcadores moleculares tipo ISSR. Materiales y métodos: Las colectas provienen de Amatitla y Zapotla en Zongolica, Veracruz. El ADN se extrajo de las hojas jóvenes. Se probaron 55 iniciadores ISSR, se seleccionaron los 10 que produjeron mayor número de bandas con polimorfismo y se amplificaron por PCR. Resultados y discusión: Los iniciadores ISSR mostraron 86 % de polimorfismo. El análisis de agrupamiento, con el método de varianza mínima de Ward, fue capaz de separar las colectas por su procedencia geográfica. El análisis de varianza molecular demostró que la mayor variabilidad (90.88 % se encuentra dentro de cada población. El índice de diversidad de Shannon-Weaver fue de 0.47 y 0.41 para Amatitla y Zapotla, respectivamente. Conclusión: Las poblaciones de M. mexicana no han sufrido cambios en su estructura genética; no hay evidencia, a nivel genético, de alteraciones ocasionadas por la reducción de poblaciones o fragmentación del hábitat.

Stability analysis of a three-phase grid-connected DC power supply with small DC-link capacitor and voltage feed-forward compensation

DEFF Research Database (Denmark)

Török, Lajos; Mathe, L.

2017-01-01

The purpose of this work was to investigate effect of the DC-link voltage feed-forward compensation on the stability of the three-phase-grid connected DC power supply, used for electrolysis application, equipped with small DC link capacitor. In case of weak grid condition, the system...

Design and Implementation of Battery Charger with Power Factor Correction using Sepic Converter and Full-bridge DC-DC Converter

Directory of Open Access Journals (Sweden)

Moh. Zaenal Efendi

2013-12-01

Full Text Available This paper presents a design and implementation of a converter which has a high power factor for battery charger application. The converter is a combination of a SEPIC converter and a full-bridge DC-DC converter connected in two stages of series circuit. The SEPIC converter works in discontinuous conduction mode and it serves as a power factor corrector so that the shape of input current waveform follows the shape of input voltage waveform. The full-bridge DC-DC converter serves as a regulator of output voltage and operates at continuous conduction mode. The experimental results show that the power factor of this converter system can be achieved up to 0.96.

Modified High Voltage Conversion Inverting Cuk DC-DC Converter for Renewable Energy Application

DEFF Research Database (Denmark)

Maroti, Pandav Kiran; Padmanaban, Sanjeevikumar; Wheeler, Patrick

2017-01-01

controlled device DC-DC topology. The voltage conversion ratio of proposed converter has increased by ten times of the conventional Cuk converterat a duty ratio of 90%. The detailed analysis of the voltage conversion ratio and losses occur due to internal resistance of components is done in the paper......The proposed exertion represents the modified high voltage conversion Cuk converter for renewable energy application. The proposed Cuk converter is a combination of the conventional boost converter and Cuk converter. The arrangement of the proposed converter make, such as, it becomes the single...

ACTIVIDADES DE LA VIDA DIARIA EN ADULTOS MAYORES: LA EXPERIENCIA DE DOS GRUPOS FOCALES

OpenAIRE

Christian Oswaldo Acosta Quiroz; Ana Luisa Mónica González-Celis Rangel

2010-01-01

El presente estudio tuvo como objetivo obtener una muestra de ejemplos de actividades recreativas físicas y mentales, sociales, de independencia y de protección a la salud, como propuesta inicial de un inventario de actividades de la vida diaria en adultos mayores, a través del desarrollo de dos grupos focales organizados alrededor del tema de actividades cotidianas en ancianos, con ocho y quince adultos mayores, respectivamente. Los resultados reflejan una amplia variedad de actividades de l...

A DC Transformer

Data.gov (United States)

National Aeronautics and Space Administration — The goal of the project was to demonstrate a true direct current (DC) transformer, a new electro-mechanical component with potentially high power applications; in...

MÉXICO Y ESTADO DE GUANAJUATO: TRANSFERENCIAS INTERGENERACIONALES HACIA LOS ADULTOS MAYORES*

Science.gov (United States)

Montes de Oca, Verónica; Hebrero, Mirna

2017-01-01

RESUMEN En México, las transferencias formales e informales destinadas al apoyo de las personas adultas mayores son diversificadas. En este documento se analizan la tendencia nacional y los resultados de un estudio centrado en la entidad federativa de Guanajuato. La distribución de los apoyos confirma que las transferencias hechas por el sistema de seguridad social tienen un sesgo urbano y que las transferencias formales del gobierno federal se orientan a las áreas menos urbanizadas, particularmente las zonas rurales. A pesar de las transferencias formales (esporádicas e insuficientes), las necesidades económicas y de salud de las personas mayores persisten y ello lleva a que sus familiares realicen transferencias informales de naturaleza ascendente. En México —y más concretamente en Guanajuato— el apoyo de quienes residen con la persona mayor tiene un significativo peso, y lo contrario sucede con el de quienes han migrado. A partir de este material, se analiza el rol que, de acuerdo a su cohorte y su condición migratoria, desempeñan los descendientes. En todo caso, queda de manifiesto que, en cada entidad nacional, las dinámicas de transferencias intergeneracionales son de diversos tipos. PMID:29375179

Exceso de peso y discapacidad en las personas mayores de la Argentina

Directory of Open Access Journals (Sweden)

Malena Monteverde

2015-01-01

Full Text Available El objetivo del presente trabajo es analizar la relación entre el exceso de peso y la condición de discapacidad en las personas mayores de la Argentina y evaluar en qué medida podría estar operando algún factor protector que reduzca o atenúe el efecto del exceso de peso sobre la pérdida de capacidades funcionales en las personas mayores de 64 años. Para ello se utilizan los microdatos de la Encuesta Nacional de Factores de Riesgo 2009. Con el objeto de medir la asociación entre sobrepeso, obesidad y la condición de discapacidad, así como la interacción de la condición de peso y la edad, se estiman modelos de regresión logística. Los resultados indican que, si bien el sobrepeso y la obesidad tendrían un efecto neto positivo sobre la presencia de discapacidades, este sería menor entre las personas de 64 años y más. Los resultados sugieren que entre las personas mayores existe algún factor protector, que si bien no revierte la relación directa entre exceso de peso y discapacidad, parece atenuarla.

Unregulated Series Resonant Converter for Interlinking DC Nanogrids

DEFF Research Database (Denmark)

Tomas Manez, Kevin; Zhang, Zhe; Ouyang, Ziwei

2017-01-01

bidirectional converter to interlink a 400V DC bus with a 48V DC bus ispresented. The proposed converter is based on a LLC resonant converter operating as a DC transformer at a fixed frequency and duty cycle without any complex control strategy. A clearand simplified design procedure for high efficiency...

Establishment of functional requirements to DC-connected wind turbine and their use in concept selection

DEFF Research Database (Denmark)

Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

2017-01-01

, but they are all still at an immature technology level, as no substantial experience from full-scale detailed design exists. By employing a functional failure mode and effects analysis (F-FMEA) with a decision making tool (Pugh Matrix), the paper presents a structured set of functionalities and design drivers...... required from the turbine DC converter and uses these to compare 6 distinct candidate circuit topologies. The end goal is not to select the best topology, but to narrow down from a vast list of options and give a method that will increase confidence and guide towards the characteristics of reliable design....

High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

Science.gov (United States)

Shimer, Daniel W.; Lange, Arnold C.

1995-01-01

A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

High voltage dc--dc converter with dynamic voltage regulation and decoupling during load-generated arcs

Science.gov (United States)

Shimer, D.W.; Lange, A.C.

1995-05-23

A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules. 5 Figs.

DC-DC Converter Topology Assessment for Large Scale Distributed Photovoltaic Plant Architectures

Energy Technology Data Exchange (ETDEWEB)

Agamy, Mohammed S; Harfman-Todorovic, Maja; Elasser, Ahmed; Sabate, Juan A; Steigerwald, Robert L; Jiang, Yan; Essakiappan, Somasundaram

2011-07-01

Distributed photovoltaic (PV) plant architectures are emerging as a replacement for the classical central inverter based systems. However, power converters of smaller ratings may have a negative impact on system efficiency, reliability and cost. Therefore, it is necessary to design converters with very high efficiency and simpler topologies in order not to offset the benefits gained by using distributed PV systems. In this paper an evaluation of the selection criteria for dc-dc converters for distributed PV systems is performed; this evaluation includes efficiency, simplicity of design, reliability and cost. Based on this evaluation, recommendations can be made as to which class of converters is best fit for this application.

SSP Technology Investigation of a High-Voltage DC-DC Converter

Science.gov (United States)

Pappas, J. A.; Grady, W. M.; George, Patrick J. (Technical Monitor)

2002-01-01

The goal of this project was to establish the feasibility of a high-voltage DC-DC converter based on a rod-array triggered vacuum switch (RATVS) for the Space Solar Power system. The RATVS has many advantages over silicon and silicon-carbide devices. The RATVS is attractive for this application because it is a high-voltage device that has already been demonstrated at currents in excess of the requirement for an SSP device and at much higher per-device voltages than existing or near-term solid state switching devices. The RATVS packs a much higher specific power rating than any solid-state device and it is likely to be more tolerant of its surroundings in space. In addition, pursuit of an RATVS-based system would provide NASA with a nearer-term and less expensive power converter option for the SSP.

Peso corporal y depresión en adultos mayores de comunidad urbano marginal en México - Tamaulipas.

OpenAIRE

Duran-Badillo, Tirso; Martínez Aguilar, Ma. de la Luz; Gutiérrez Sánchez, Gustavo; Rosa Ma., Rosa Ma.; Guevara-Valtie, Milton Carlos

2016-01-01

El peso corporal inadecuado y la depresión son factores que alteran la calidad de vida del adulto mayor. Objetivos: identificar asociación existente entre peso corporal y depresión en el adulto mayor. Material y Metodos: estudio descriptivo y correlacional, se realizó en una población urbano-marginal de Tamaulipas, México. Participaron 252 adultos mayores de 60 años y que tuvieran la capacidad física para mantenerse de pié al momento de medir el peso corporal y talla. El muestreo fue no proba...

DC-Evoked Modulation of Excitability of Myelinated Nerve Fibers and Their Terminal Branches; Differences in Sustained Effects of DC.

Science.gov (United States)

Kaczmarek, Dominik; Jankowska, Elzbieta

2018-03-15

Direct current (DC) evokes long-lasting changes in neuronal networks both presynaptically and postsynaptically and different mechanisms were proposed to be involved in them. Different mechanisms were also suggested to account for the different dynamics of presynaptic DC actions on myelinated nerve fibers stimulated before they entered the spinal gray matter and on their terminal branches. The aim of the present study was to examine whether these different dynamics might be related to differences in the involvement of K + channels. To this end, we compared effects of the K + channel blocker 4-amino-pyridine (4-AP) on DC-evoked changes in the excitability of afferent fibers stimulated within the dorsal columns (epidurally) and within their projection areas in the dorsal horn and motor nuclei (intraspinally). 4-AP was applied systemically in deeply anesthetized rats. DC-evoked increases in the excitability of epidurally stimulated afferent nerve fibers, and increases in field potentials evoked by these fibers, were not affected by 4-AP. In contrast, sustained decreases rather than increases in the excitability of intraspinally stimulated terminal nerve branches were evoked by local application of DC in conjunction with 4-AP. The study leads to the conclusion that 4-AP-sensitive K + channels contribute to the sustained DC-evoked post-polarization increases in the excitability at the level of terminal branches of nerve fibers but not of the nodes of Ranvier nor within the juxta-paranodal regions where other mechanisms would be involved in inducing the sustained DC-evoked changes. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Predictive Trailing-Edge Modulation Average Current Control in DC-DC Converters

Directory of Open Access Journals (Sweden)

LASCU, D.

2013-11-01

Full Text Available The paper investigates predictive digital average current control (PDACC in dc/dc converters using trailing-edge modulation (TEM. The study is focused on the recurrence duty cycle equation and then stability analysis is performed. It is demonstrated that average current control using trailing-edge modulation is stable on the whole range of the duty cycle and thus design problems are highly reduced. The analysis is carried out in a general manner, independent of converter topology and therefore the results can then be easily applied for a certain converter (buck, boost, buck-boost, etc.. The theoretical considerations are confirmed for a boost converter first using the MATLAB program based on state-space equations and finally with the CASPOC circuit simulation package.

Control of hybrid AC/DC microgrid under islanding operational conditions

DEFF Research Database (Denmark)

Ding, G.; Gao, F.; Zhang, S.

2014-01-01

This paper presents control methods for hybrid AC/DC microgrid under islanding operation condition. The control schemes for AC sub-microgrid and DC sub-microgrid are investigated according to the power sharing requirement and operational reliability. In addition, the key control schemes...... of interlinking converter with DC-link capacitor or energy storage, which will devote to the proper power sharing between AC and DC sub-microgrids to maintain AC and DC side voltage stable, is reviewed. Combining the specific control methods developed for AC and DC sub-microgrids with interlinking converter......, the whole hybrid AC/DC microgrid can manage the power flow transferred between sub-microgrids for improving on the operational quality and efficiency....

Ciudad educadora y nuevos espacios de educación para la salud en las personas mayores

Directory of Open Access Journals (Sweden)

M.\\"* Rosario Limón Mendizábal

2001-01-01

Full Text Available Mantenerse sano y con el mayor grado de autonomía y bienestar es uno de los requisitos más importantes para disfrutar de una jubilación satisfactoria. Cada persona tiene la potencialidad para asumir la responsabilidad que le corresponde en el cuidado de su propia salud. En la actualidad hay una mayor demanda de información sobre el cuidado de la salud. Esto se debe a que hay una mayor conciencia de que la salud es, en gran medida, responsabilidad nuestra y no de los profesionales de la salud (médicos, sanitarios..., como antes se creía. En la implantación y desarrollo de las disciplinas “Educación para la salud”, “Educación de las personas mayores” o “Gerontología educativa” en la Universidad española, ha sido fundamental la progresiva consolidación de la Pedagogía Social. Desde la perspectiva de la Ciudad educadora, analizamos en este artículo los distintos Espacios para Mayores donde se desarrollan programas de educación para la salud a través de talleres (de memoria, de autoestima, de pensamiento positivo y alegría de vivir, de hábitos saludables, de técnicas de relajación..., seminarios, grupos de debate, conferencias, cursos, charlas... Estos espacios han pasado de tener un carácter asistencial en los años setenta, a una concepción socio-educativa y cultural, dirigida a favorecer la participación y formación continua de los adultos mayores, en la entrada al nuevo milenio. Son espacios de aprendizaje, en definitiva, espacios de vida donde compartir información, experiencias y formación con el fin de envejecer de manera saludable y potenciar el desarrollo personal en esta nueva etapa de la vida. Por último, presentamos un curso sobre “Promoción de la salud y bienestar de los mayores” para ser desarrollado a través de grupos de debate

Analisa Perbandingan Efisiensi Motor Dc Kompon Pendek Dengan Motor Dc Kompon Panjang Akibat Penambahan Kutub

OpenAIRE

Sitompul, Fuad Rahim

2015-01-01

Motor listrik merupakan perangkat elekromagnetis yang mengubah energi listrik menjadi energi mekanik. Motor DC memerlukan tegangan searah pada kumparan medan untuk diubah menjadi energi mekanik. Energi mekanik ini digunakan sebagai penggerak peralatan listrik seperti pompa,penggerak kipas angin, lift dan lain-lain. Karena penggunaannya yang cukup luas maka kinerjanya harus baik. Kinerja suatu motor DC dikatakan baik jika efisiensi motor tersebut tinggi. Hal itu dapat dicapai dengan mengatur b...

A soft-switching coupled inductor bidirectional DC-DC converter with high-conversion ratio

Science.gov (United States)

Chao, Kuei-Hsiang; Jheng, Yi-Cing

2018-01-01

A soft-switching bidirectional DC-DC converter is presented herein as a way to improve the conversion efficiency of a photovoltaic (PV) system. Adoption of coupled inductors enables the presented converter not only to provide a high-conversion ratio but also to suppress the transient surge voltage via the release of the energy stored in leakage flux of the coupled inductors, and the cost can kept down consequently. A combined use of a switching mechanism and an auxiliary resonant branch enables the converter to successfully perform zero-voltage switching operations on the main switches and improves the efficiency accordingly. It was testified by experiments that our proposed converter works relatively efficiently in full-load working range. Additionally, the framework of the converter intended for testifying has high-conversion ratio. The results of a test, where a generating system using PV module array coupled with batteries as energy storage device was used as the low-voltage input side, and DC link was used as high-voltage side, demonstrated our proposed converter framework with high-conversion ratio on both high-voltage and low-voltage sides.

Solar Photovoltaic DC Systems: Basics and Safety: Preprint

Energy Technology Data Exchange (ETDEWEB)

McNutt, Peter F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sekulic, William R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dreifuerst, Gary [Lawrence Livermore National Laboratory - retired

2018-04-02

Solar Photovoltaic (PV) systems are common and growing with 42.4 GW installed capacity in U.S. (almost 15 GW added in 2016). This paper will help electrical workers, and emergency responders understand the basic operating principles and hazards of PV DC arrays. We briefly discuss the following aspects of solar photovoltaic (PV) DC systems: the effects of solar radiation and temperature on output power; PV module testing standards; common system configurations; a simple PV array sizing example; NEC guidelines and other safety features; DC array commissioning, periodic maintenance and testing; arc-flash hazard potential; how electrical workers and emergency responders can and do work safely around PV arrays; do moonlight and artificial lighting pose a real danger; typical safe operating procedures; and other potential DC-system hazards to be aware of. We also present some statistics on PV DC array electrical incidents and injuries. Safe PV array operation is possible with a good understanding of PV DC arrays basics and having good safe operating procedures in place.

Factores que inciden en la soledad residencial de las personas mayores que viven solas

OpenAIRE

Julia Gallo Estrada; Jesús Molina Mula

2015-01-01

El aumento de la esperanza de vida, los cambios sociales y los cambios en la estructura familiar hacen que cada vez sean más y durante más tiempo las personas mayores que prefieren vivir solas, incluso cuando necesitan cuidados. Este trabajo tiene como objetivo describir el problema de la soledad residencial de las personas mayores profundizando en los factores que pueden influir en esta circunstancia. Se ha realizado una estrategia de búsqueda bibliográfica a partir de los conceptos nucleare...

Digital DC beam current measurement on SSRF storage ring

International Nuclear Information System (INIS)

Xiong Liang; Yin Chongxian; Liu Ming; Chen Jianfeng

2011-01-01

Both DC current transformer (DCCT) and integrating current transformer (ICT) can be used in DC beam current measurement. The ICT has strong capability of resisting electromagnetic interference, but its measurement accuracy cannot satisfy the DC beam current measurement requirement when using traditional high speed A/D. With high resolution A/D and equivalent sampling system, DC beam current measuring system based on ICT can reach high accuracy compared with DCCT system. In this paper, the ICT-based DC beam current measurement, equivalent sampling method and testing results at Shanghai Synchrotron Radiation Facility(SSRF) is described. (authors)

Violencia intrafamiliar en el adulto mayor que vive en el distrito de Breña, Perú

Directory of Open Access Journals (Sweden)

Jack Roberto Silva Fhon

2015-07-01

Full Text Available Antecedentes: La violencia hacia el adulto mayor es un problema social que ocurre dentro de la familia y que por miedo no es denunciado dificultando el trabajo del personal multi-profesional de salud para la detección, denuncia y prevención de estos casos. Objetivo: Identificar la prevalencia, los tipos de violencia intrafamiliar e su asociación con variables socio demográficas y presencia de síntomas depresivos en el adulto mayor que vive en la comunidad. Método: Estudio cuantitativo, descriptivo y transversal con 369 adultos mayores en el distrito de Breña, Lima – Perú. Se utilizó el instrumento de datos sociodemográficos, Canadian Task Force on the Periodic Health Examination y Escala de Depresión Geriátrica. Para el análisis de los datos se aplicó estadística descriptiva y regresión logística. Resultados: Predominó el sexo femenino, adulto mayor más joven, el estado civil casado y la conformación familiar por el cónyuge. La prevalencia de violencia intrafamiliar fue 79,7% y síntomas depresivos 48,2%. Prevaleció la violencia financiera. A la regresión se verificó que aquel que no trabaja tiene mayor chance de sufrir de violencia. Cuanto más son los años de estudio disminuye el riesgo de sufrir de violencia. Asimismo, aquel que no presenta síntomas depresivos no sufre de violencia. Conclusión: Se verificó que el adulto mayor necesita de atención permanente y que el personal de salud debe reconocer síntomas y señales en el adulto mayor que sufre de violencia y que presenta síntomas depresivos ofreciendo información con la importancia de denunciar estos casos favoreciendo un envejecimiento saludable y con calidad.

Will Mayor De Blasio Turn Back the School Reform Clock?

Science.gov (United States)

Meyer, Peter

2014-01-01

While heads were spinning, policy watchers seemed genuinely perplexed by New York City's Mayor de Blasio's education opinions. De Blasio opposed many of Bloomberg's reform efforts despite the achievement gains realized by the nation's largest school district during the last 12 years. Yet on close reading, de Blasio's nine-page education plan…

Comportamiento clínico epidemiológico del grupo de adultos mayores del Centro de Salud Tosagua, año 2016

Directory of Open Access Journals (Sweden)

Jorge Javier Bergues

2018-03-01

Conclusiones: El grupo estudiado estuvo integrado mayormente por adultos mayores de menos de 70 años y predomino el sexo femenino. La hipertensión como entidad que principalmente presentaron los ancianos. Durante el periodo estudiado la mayoría de los hipertensos se mantuvieron compensados; sin embargo, la mayoría de los pacientes con diabetes mellitus estuvieron descompensados. El losartán es el antihipertensivo más utilizado. La metformina es el hipoglucemiante de mayor uso.

Method to predetermine current/power flow change in a dc grid

DEFF Research Database (Denmark)

2017-01-01

occurs at one of the AC/DC converters; establishing a generalized droop feedback gain matrix G; controlling current/power flow within DC grid towards predefined setpoints, by use of control law. The invention presents an analytical approach to derive the generalized feedback gain allowing......The invention relates to a method for controlling current/power flow within a power transmission system, comprising two or more interconnected converter stations. The method comprises the steps of: providing a DC admittance matrix given from the DC grid; providing a current distribution matrix...... for a number of, such as for all possible AC/DC converter outages; providing a DC bus voltage vector for the DC grid; the DC bus voltage vector being a vector containing the values of the voltage change at the AC/DC converters, measured at the AC/DC converters, before, during and after a forced current change...

Gambaran Status Gizi Anak Talasemia β Mayor di RSUP Dr. M. Djamil Padang

Directory of Open Access Journals (Sweden)

Dona Mirsa Putri

2015-09-01

Full Text Available Abstrak  Talasemia merupakan penyakit kronik yang membutuhkan transfusi setiap bulan, karena eritrosit lebih cepat lisis dibandingkan eritrosit normal. Komplikasi dan efek penyakit ini banyak, antara lain pertumbuhan, perkembangan, dan status gizinya. Penelitian ini bertujuan  mengetahui gambaran  status gizi anak talasemia β mayor Penelitian iniadalah penelitian deskriptif yang  dilakukan pada bulan Februari 2012 - Maret 2013 di RSUP Dr. M. Djamil Padang dengan sampel anak talasemia β mayor. Pemeriksaan yang dilakukan adalah mengukur tinggi badan, berat badan, dan lingkar lengan. Hasil pemeriksaan dimasukkan dalam tabel persentil NCHS dan penilaian status gizi berdasarkanDepartemen Kesehatan Repubik Indonesia.Hasil penelitian ini terdapat 15 anak talasemia β mayor, dengan rata-rata umur kelompok 5-10 tahun. Frekuensi terbanyak indeks tinggi badan per umur yaitu 70%-90% (60%.. Frekuensi terbanyak indeks berat badan per umur adalah 60%-80% (66.7%. Frekuensi terbanyak indeks lingkar lengang atas per umur adalah 70%-85% (80%. Simpulan dari hasil penelitian status gizi anak talasemia β mayor adalah gizi kurang.Kata kunci: Status gizi, talasemia β mayorAbstract Thalassemia is a chronic disease who needs blood tranfusion every month because the abnormal erythrocyte has short life time compared with the normal erythrocyte. There are so many complications and effects of this disease, such as growth and nutritional status. The aim of this research is to describe chlidren's nutritional status with thalassemia beta major. This research is a descriptive research. It has been done since February 2012 - March 2013 at RSUP Dr.  M. Djamil Padang. The sampling is children with thalassemia beta major. The examination are stature, weight, and upper arm circumference and the result is entered into NHCS percentil and assessment of Nutritional based on health department of Indonesia. From this research, there are 15 children who are suffering thalassemia

Development of AC-DC power system simulator

International Nuclear Information System (INIS)

Ichikawa, Tatsumi; Ueda, Kiyotaka; Inoue, Toshio

1984-01-01

A modeling and realization technique is described for realtime plant dynamics simulation of nuclear power generating unit in AC-DC power system simulator. Dynamic behavior of reactor system and steam system is important for investigation a further adequate unit control and protection system to system faults in AC and DC power system. Each unit of two nuclear power generating unit in the power system simulator consists of micro generator, DC motors, flywheels and process computer. The DC motor and flywheel simulates dynamic characteristics of steam turbine, and process computer simulates plant dynamics by digital simulation. We have realized real-time plant dynamics simulation by utilizing a high speed process I/O and a high speed digital differential analyzing processor (DDA) in which we builted a newly developed simple plant model. (author)

Modeling and simulation for micro DC motor based on simulink

Science.gov (United States)

Shen, Hanxin; Lei, Qiao; Chen, Wenxiang

2017-09-01

The micro DC motor has a large market demand but there is a lack of theoretical research for it. Through detailed analysis of the commutation process of micro DC motor commutator, based on micro DC motor electromagnetic torque equation and mechanical torque equation, with the help of Simulink toolkit, a triangle connection micro DC motor simulation model is established. By using the model, a sample micro DC motor are simulated, and an experimental measurements has been carried on the sample micro DC motor. It is found that the simulation results are consistent with theoretical analysis and experimental results.

LA DIVERSIFICACIÓN Y CONSOLIDACIÓN DE LOS SERVICIOS SOCIALES PARA LAS PERSONAS MAYORES EN ESPAÑAY SUECIA

Directory of Open Access Journals (Sweden)

María Dolores Puga González

2011-01-01

Full Text Available La información sobre los servicios públicos para las personas mayores a menudo se limita a la atención residencial y a la ayuda a domicilio. Sin embargo, estos servicios básicos son en muchos países complementados o sustituidos por otros servicios de menor envergadura, como el transporte, comidas a domicilio, teleasistencia y centros de día. Esta diversificación partió de un racionamiento de los servicios para lograr una asignación más racional de los recursos y, si se podía, un menor gasto. En este trabajo se utilizan diversos datos sobre estos servicios en España y Suecia. Cuando se consideran todos los cuidados, la cobertura de atención es mucho mayor que si sólo se contemplan los servicios básicos. Esto indica una mayor consolidación de los mismos. Los datos sugieren mayor focalización en Suecia, y prestaciones fragmentadas en España, donde parece que los usuarios alcanzan lo disponible, con poca diferenciación entre sus necesidades. Cuando las tasas de cobertura son superiores, como en Suecia, hay mayor solapamiento entre el cuidado familiar y los servicios públicos. Con tasas más bajas, como en España, los cuidados familiares y los servicios públicos son sustitutos unos de otros. Se sugiere que una mayor diversidad de servicios, básicos y secundarios, puede adaptarse mejor y de manera más eficiente a las diversas necesidades de las personas mayores que la elección entre ningún servicio, ayuda domiciliaria o atención residencial. Aunque estos servicios secundarios también puedan ser utilizados como un sustituto de bajo coste, e inferior calidad, en la atención.

Cuidado popular de familias con un adulto mayor sobreviviente del primer accidente cerebrovascular

Directory of Open Access Journals (Sweden)

Lucero López-Díaz

2016-01-01

Full Text Available Introducción: el accidente cerebrovascular afecta a numerosas personas en el mundo y se constituye en la principal causa de muer- te. Los sobrevivientes pueden padecer discapacidad y sufrir modificaciones en las actividades cotidianas. La familia es el principal apoyo del sobreviviente y al ser parte de una misma cultura, construye acciones de cuidado en búsqueda del bienestar. Objetivo: describir las acciones del cuidado popular de las familias con un adulto mayor sobreviviente del primer accidente cerebrovascular. Método: estudio etnográfico, con observación participante y entrevistas en profundidad. Participaron siete familias bogotanas (siete adultos mayores entre los dos y diez meses posteriores al primer accidente cerebrovascular y los siete cuidadores principales respectivos. Resultados: cuidadores y adulto mayor comparten acciones de cuidado para la recuperación, relacionadas con la alimentación, el cuidado personal y la ingesta de medicamentos permeadas por la creencia religiosa, fuente de soporte y vínculo afectivo. Conclusión: conocer el cuidado popular de esta población posibilita proponer acciones culturalmente congruentes con sus valores y creencias para potencializar las ca- pacidades familiares e intermediar en los procesos de tratamiento.

Comparison of two different high performance mixed signal controllers for DC/DC converters

DEFF Research Database (Denmark)

Jakobsen, Lars Tønnes; Andersen, Michael Andreas E.

2006-01-01

This paper describes how mixed signal controllers combining a cheap microcontroller with a simple analogue circuit can offer high performance digital control for DC/DC converters. Mixed signal controllers have the same versatility and performance as DSP based controllers. It is important to have...... an engineer experienced in microcontroller programming write the software algorithms to achieve optimal performance. Two mixed signal controller designs based on the same 8-bit microcontroller are compared both theoretically and experimentally. A 16-bit PID compensator with a sampling frequency of 200 k......Hz implemented in the 16 MIPS, 8-bit ATTiny26 microcontroller is demonstrated....

Loss Modelling and Experimental Verification of A 98.8% Efficiency Bidirectional Isolated DC-DC Converter

Directory of Open Access Journals (Sweden)

Ramachandran Rakesh

2017-01-01

In this paper, design and implementation of an ultra-high efficiency isolated bi-directional dc-dc converter utilizing GaN devices is presented. Loss modelling of the GaN converter is also included in this paper. The converter has achieved a maximum measured efficiency of 98.8% in both directions of power flow, using the same power components. Hardware prototype of the converter along with the measured efficiency curve is also presented in this paper.

Impact of Faults and Protection Methods on DC Microgrids Operation

DEFF Research Database (Denmark)

Bayati, Navid; Hajizadeh, Amin; N. Soltani, Mohsen

2018-01-01

with the DC Microgrid. This paper evaluates and presents a comprehensive review on the most recent studies in the DC Microgrids protection. Moreover, the fault behavior and characteristics of DC Microgrids, the effect of Constant Power Load (CPL) , and recent DC Microgrid protection methods are reviewed. Also...

Blind signal processing algorithms under DC biased Gaussian noise

Science.gov (United States)

Kim, Namyong; Byun, Hyung-Gi; Lim, Jeong-Ok

2013-05-01

Distortions caused by the DC-biased laser input can be modeled as DC biased Gaussian noise and removing DC bias is important in the demodulation process of the electrical signal in most optical communications. In this paper, a new performance criterion and a related algorithm for unsupervised equalization are proposed for communication systems in the environment of channel distortions and DC biased Gaussian noise. The proposed criterion utilizes the Euclidean distance between the Dirac-delta function located at zero on the error axis and a probability density function of biased constant modulus errors, where constant modulus error is defined by the difference between the system out and a constant modulus calculated from the transmitted symbol points. From the results obtained from the simulation under channel models with fading and DC bias noise abruptly added to background Gaussian noise, the proposed algorithm converges rapidly even after the interruption of DC bias proving that the proposed criterion can be effectively applied to optical communication systems corrupted by channel distortions and DC bias noise.

Maltrato intrafamiliar hacia el adulto mayor en el del Policlínico Reynold García de Versalles

OpenAIRE

García Rosique, Regla Mercedes; Guisado Zamora, Katia; Torres Triana, Adelaida

2016-01-01

Introducción: el maltrato al adulto mayor emerge como problema social, desde hace pocos años, y no porque antes no existiera, sino porque muchas veces existe en las familias y no sale a la luz pública. Objetivo: identificar maltrato intrafamiliar hacia los adultos mayores. Materiales y Métodos: se realizó un estudio descriptivo, de corte transversal en 60 adultos mayores de 60 años, pertenecientes al Consultorio Médico de Familia No. 87, del Policlínico Reynold García, área de Versalles de la...

Los Centros y espacios de actividad física utilizados por las personas mayores en España

OpenAIRE

Jiménez-Beatty Navarro, Jose Emilio; Martínez del Castillo, Jesus; Hierro Pinés, David del; Martin Rodriguez, Maria; González Rivera, Maria Dolores

2008-01-01

El objeto de la comunicación ha consistido en abordar las instalaciones y espacios utilizados por las personas mayores que realizan actividad física semanalmente. El método ha consistido en la realización de una encuesta, en la que mediante entrevista personal se ha aplicado un cuestionario a una muestra aleatoria de la población de personas mayores en España. Los resultados muestran que la mayor parte de estas personas practican en espacios cubiertos y de instalaciones deportivas (sobre todo...

Bifurcation diagram features of a dc-dc converter under current-mode control

International Nuclear Information System (INIS)

Ruzbehani, Mohsen; Zhou Luowei; Wang Mingyu

2006-01-01

A common tool for analysis of the systems dynamics when the system has chaotic behaviour is the bifurcation diagram. In this paper, the bifurcation diagram of an ideal model of a dc-dc converter under current-mode control is analysed. Algebraic relations that give the critical points locations and describe the pattern of the bifurcation diagram are derived. It is shown that these simple algebraic and geometrical relations are responsible for the complex pattern of the bifurcation diagrams in such circuits. More explanation about the previously observed properties and introduction of some new ones are exposited. In addition, a new three-dimensional bifurcation diagram that can give better imagination of the parameters role is introduced

Electrothermal model of choking-coils for the analysis of dc-dc converters

Energy Technology Data Exchange (ETDEWEB)

Gorecki, Krzysztof, E-mail: gorecki@am.gdynia.pl [Gdynia Maritime University, Department of Marine Electronics, Morska 83, Gdynia (Poland); Detka, Kalina [Pomeranian Higher School in Gdynia, Opata Hackiego 8-10, Gdynia (Poland)

2012-09-01

The paper concerns modelling the choking-coil for the needs of the electrothermal analysis of dc-dc converters. A new electrothermal model of the choking-coil is proposed. This model is dedicated for SPICE software and it takes into account nonlinearity of the dependences of the inductance on the current, selfheating and mutual thermal interactions between the core and the winding. The structure of this model is described in detail and its correctness is experimentally verified for the choking-coils with the ferrite and powder cores. Both the characteristics of the choking-coils and the buck converter with these choking-coils were considered. The satisfying agreement between the results of calculations and measurements is obtained.

A VHF Class E DC-DC Converter with Self-Oscillating Gate Driver

DEFF Research Database (Denmark)

Andersen, Toke Meyer; Christensen, Søren K.; Knott, Arnold

2011-01-01

, is inherently resonant, and switching losses are greatly reduced by ensuring Zero Voltage Switching (ZVS) of the power semiconductor devices. A design method to ensure ZVS operation when combining the inverter, rectifier, and gate driver is provided. Several parasitic effects and their influence on converter......This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz − 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver...... operation are discussed, and measurement results of a 100 MHz prototype converter are presented and evaluated. The designed prototype converter verifies the described topology....

Attitudes and Perceptions of Vocational Education in New York City: Implications for the Mayor's School Reform Initiative

Science.gov (United States)

Green, Rupert

2012-01-01

Under-performing New York City (NYC) schools precipitated Mayor Michael Bloomberg's decision to advance a vocational education initiative. The initiative was to address the problem of the many city high school graduates lacking both the skills for gainful employment and the academic preparedness to pursue higher education. The mayor's initiative…

RELACIÓN DE HELICOBACTERIOSIS EN CANINOS Y SUS PROPIETARIOS EN DIFERENTES ESTRATOS SOCIOECONÓMICOS EN BOGOTÁ D.C.

Directory of Open Access Journals (Sweden)

Diana Naranjo Restrepo

2012-07-01

Full Text Available El presente trabajo determinó la asociación de helicobacteriosis en caninos con sus propietarios en Bogotá D. C, durante marzo de 2007 y enero de 2008; el estudio fue observacional descriptivo de corte transversal correlacional. La encuesta se aplicó a 34 propietarios de mascota canina, seleccionadas en 12 localidades de Bogotá D.C. Esta contenía información del propietario y del animal. La unidad muestral correspondió a casas habitadas que cumplían los criterios de inclusión, analizando los títulos séricos de IgM por la técnica ELISA para Helicobacter pylori en caninos y sus propietarios. Se utilizó el programa estadístico SPSS15.0 para Windows y Prueba de Correlación de Pearson conuna muestra en los estratos 1, 3 y 6. Se relacionaron las variables de títulos de IgM en Humano y animal. (R= 0.87 La correlación fue de 87,3%. Se encontró mayor título de IgM en humanos (12.5en estrato 1 seguido de 3 y 6. En caninos, el mayor título de IgM (+/-12.5 correspondió al estrato 1seguido de 3 y 6, encontrándose los títulos más altos de IgM en Ciudad Bolívar, Usme y Usaquén. En cuanto a humanos, las localidades con mayor título de IgM fueron Usme, Puente Aranda y Antonio Nariño. La edad estudiada fue entre 15 a 70 años, siendo los títulos IgM de 30 a 60 años. El género femenino mostró títulos de IgM más altos con una prevalencia entre 2 +/- 6.5. Se halló una correlación de 87,3% con los títulos del propietario y la mascota demostrando asociación de helicobacteriosis en caninos con sus propietarios.